We’ve taken Platypus Tours a couple times previously, and I highly recommend them for wine tasting/touring in the Napa/Sonoma area. Platypus takes you to more of the boutique and unusual wineries you would probably not find on your own, and/or arranges for semi or private tastings at their winery stops. Platypus utilizes mid-size bus vans, which seat perhaps 14 people in a semi-circular arrangement, with an aisle in the middle. 
They normally don’t have more than 10 people, so it’s quite a comfortable and safe way to tour the wineries. Platypus is very flexible with their scheduling, and do their best to take your individual preferences in mind, which should be specified when you are booking. (The guide usually finalizes their itinerary the evening before, subject to minor changes, i.e. due to group size etc.) Since we had toured the Sonoma area with them a couple times, we asked to tour other vineyards we had not been to, and only one of the four we went to on this tour was duplicated from previous visits. Even the one winery we had previously been to (Petroni) now had the wine caves open to taste in (instead of the actual home we did before) which was a nice end-of-day treat, so it was a new experience for us as well.
Our day started with in-room coffee sitting on our balcony at the 
Ledson Hotel. 
Steve DOS went to the lobby and brought 
back some delicious pastries, which we enjoyed on our balcony overlooking the quaint downtown Sonoma area. As you don’t want to tour the wineries on an empty stomach, we then ventured around the square for an extra quick breakfast snack to go, as the Ledson Hotel is not open for a full breakfast.
Our pickup time for Platypus (they pick you up right at your hotel) was 10:30am, and Evonne, our tour guide for the day, was right on time. As soon as we got on the mini-bus, we knew were in with a fun group! 
There was already a group of five (four gals and one guy) that were picked up at another stop, and were all vacationing together. All were originally from Wisconsin, although one couple lives in San Francisco, one in Chicago, and the other gals in Wisconsin. They were a young and fun group!
We made one more stop, and picked up two more girls, one from the Philly area, and the other living in the SF Bay area, who were friends traveling together. We all quickly re-introduced ourselves, and knew that the 9 of us were in for a fun day! Evonne then explained our tour schedule for the day, and reminded us to drink a bottle of complimentary water after every stop to stay hydrated. Good advice, and we did raid the onboard cooler for a fresh bottled water each stop. Evonne doubles as a Chef and Event Coordinator and she was very knowledgeable about wines. Evonne’s catering website is FoodStylistChef.com, and the food looks yummy!
As I said earlier, the bus/vans Platypus uses are quite comfortable, and I actually prefer them to the various limo services that offer similar tours. We took a shared stretched limo tour from another vendor a couple years ago in Napa, and though it was quite nice, it was actually not as comfortable as the Platypus mini-buses. On the stretched limos, you don’t have as much room as in the bus, and you are lower to the ground, so your view of the passing wine country is not as good.
On this, as on other Platypus tours, we stopped at four wineries, with lunch (included) after the first winery. Tasting fees are not included, which averages around $15 a stop, but some will waive the fee if you purchase a few bottles of wine.
Our first winery stop of the day was Buena Vista Winery, which bills itself as the oldest premium winery in California, dating back to 1857. 
I had been there over 20 years ago, and wouldn’t have recognized it today, due to the millions of $$$ the new owners have invested in it. Somewhere in my old, non-digital photos I have some pics of it way back then, which I remember being very rustic with ivy covering the old buildings. If I find it, I’ll post it later, but here it is today in 2015.
Yvonne introduced us to our Buena Vista tour guide, Brandon, and for the next 75 
minutes or so we tasted wines and took an interesting tour thru some of the original caves. We literally did both simultaneously, as we started in the tasting room with Brandon, 
and then took our glass with us on the tour, while Brandon kept a bottle handy for refills, and later finished up in the same tasting room.
Unfortunately the winery had earthquake damage over the years, but two of the main buildings are still standing, although have had to be (and still are) structurally updated. This winery had some really interesting touches, and private tasting rooms you could reserve. 
In one you can dress up in attire of the period and even bottle your own vino creation you make there. No guarantees of the taste of course, but sounds like fun and would make for some great photos and memories!
Another fun room was the ‘Bubbles’ room, where you can sample Sparkling Wines in a theatrical setting.
The Bubbles room is decorated with an eclectic set of props, complete with mannequins, sofas, antiques, a player piano, 
and bar – you’d think you were in the dressing room of a Hollywood movie set! You could even hear the piano playing as we toured the long halls of the caves. Quite original touch, adding to the rumors of the haunted caves inside!
At each winery we bought either some wines to take home, or have shipped back. That’s what we like about touring Sonoma/Napa and any wine region for that matter, as you can get premium wines not available in stores. We had brought with us a couple of wine carriers we had purchased last visit to Sonoma, so we were prepared to check in the wines for the flight home.
Our next stop was Homewood Winery. 
This small winery (their web site says: “is as close to a one man winery as David Homewood can keep it”) sources it’s grapes, but makes nice and inexpensive wines compared to others in the area. A seasoned wine consultant (i.e. he had been working in the area for many years) talked for awhile about the wine process and history of the winery/region, and then served us quite a few different types of wines. 
We had lunch there in the private outdoor gazebo with our group, and bought a bottle to share with others over lunch, as did Kyle and the girls. We bought a Cabernet, while the others got a Merlot. We could hear (and see if we walked out of the Gazebo) the Mariachi band playing across the street at the Caneros Brewery. Looked and sounded like a lot of fun – note to self, try that next time as well!
Our next stop was Madrone Vineyards Estate. 
We overstayed our lunch time a bit at Homewood winery, so we only had 45 minutes at Madrone as Evonne wanted to make sure we had plenty of time for the last stop. This was a lovely winery and we had a great wine tour guide here named Sue. This would be a nice place to have a relaxing glass of wine and cheese plate on the patio enjoying the great weather with no worries of time. Like Buena Vista, this is one of the oldest vineyards in the area, originally dating back to 1863, which their wine club appropriately titles ‘Club 1863’.
Here we sampled several nice wines outdoors under bright colored umbrellas, which shaded us from the warm California sun – what a beautiful day it was!
Our last stop was Petroni Vineyards which sits high upon the vineyard hills and offers spectacular views of the surrounding area. On the way there, we were treated to some ‘heavy’ (not sure what the music type is!) 
music that the Wisconsin group had brought aboard, and Evonne let them play it thru the overhead speakers. Wow – by this time everyone was jamming!
As Petroni Vineyards is actually the private residence of the family, tours are by pre-arranged appointment only. Petroni’s actual tasting room is in downtown Sonoma, so we were glad to be invited guests. The gated entrance ensures the family privacy, and it’s not a place you would normally get to tour on your own – thanks Platypus!
We did tour this estate a couple years ago (again with Platypus), but at the time the tasting was actually done on the grounds by their pool. The humongous wine caves (where we went this time), were still being built, and are located right below the estate area, just steps away from the home. We felt fortunate to have toured inside the home and pool area on the last visit, and now could see the finished product of the massive caves, where we had our wine tasting – we got to see the best of both! Since it was quite dark in the actual caves, we did not take any photos inside. Here are some photos of the pool area and house taken on our previous tour in Sept 2013.
There is also a nice video you can see of the property that was showing on the TV inside the house, 
and is now show in the caves as well. You can see this Petroni video online at their website.
Our tour and tasting today was held in the caves, and the caves was quite an amazing feat to have built. As I said it was quite dark, even with the low level lighting, but you could see as we walked along it was quite open and lengthy, with wine barrels along the way, and mini-alcoves scattered throughout, each set up with tables for a wine tasting. It was in one of these alcoves that we had our wine tasting – quite good wines, in a very unique setting. We had a mixed case shipped home from Petroni we enjoyed it so much, as well as some of their wonderful olive oil which Italians are know for. Our wine consultant served olive oil and bread with the tasting, and the olive oil was rich and flavorful.
But finally, by 5pm or so, it was time for our tour to come to an end. We had a group picture taken by Yvonne outside the caves, and here are a couple others showing the magnificent views.
‘Twas a fun day for all!