I'm super cheap, in case you hadn't noticed (typed the girl who buys clothes at the Salvation Army, but only on Wednesdays when they're half-price, then resells them on Ebay). So, even though I treat myself when I'm on vacation, I don't like to waste money. So here are my money-saving tips for Sonoma.
1. Rent a car. It is far more expensive to get a taxi all the way from SFO to Sonoma, and a car service or shuttle from vineyard to vineyard isn't necessary. If you're just tasting, not drinking, you won't get tipsy - especially if you take your time and enjoy the scenery after each tasting.
2. Stay centrally. Cut down on gas and costs by staying in an inexpensive hotel in Santa Rosa. You won't be in it for more than sleeping, and it's a short drive to most areas.
3. Do your homework. I picked out 4 - 5 tasting rooms that offered free tastings for each day. We usually didn't make it to all of them, but it gave us options. I see no reason to pay for tastings: small, quality vineyards want you to taste their product, and will tell you all about it. Larger, commercial productions charge $10 to $20 a person and aren't as personal (and really, who wants to taste Coppola wines? You can buy them at the grocery store).
4. Bring a big, nylon check-bag. Bring it empty, and stuff it in a carry-on for the ride up. Some tasting rooms charge $10 a taste - waived with a purchase. Use this as a reason to buy wine for yourself and as gifts - whenever there's a waivable charge, buy a bottle. Then ask a restaurant or grocery store for an empty wine box and paper and pack it up with all your bottles before zipping it into your luggage. You save the tasting fee, and rack up on all different types of wine. Keep the tasting going!
5. See the outdoors. Absolutely hike in Armstrong Redwood Park and absolutely spend time at several of the Pacific beaches. Breathtaking beauty at both places and of course, free. Pack a picnic!
6. Bring a book to Preston winery. Taste the wine, then have the fee waived when you buy a bottle of sauvignon blanc. Their bakery makes great sourdough bread and their farm produces fresh produce - you can buy a whole lunch for two (with leftovers!) including the wine for under $40. Then sit outside for your picnic and read the afternoon away, sipping wine.
7. Plan to visit some tasting rooms that are open late. There isn't a lot going on at night in Sonoma most of the time, and if you've been tasting wine all night you might not want to spend the evening in a bar getting another drink. But you're left with a lot of time in the evening: if the tasting rooms close at 4 or 5, you tend to find a restaurant and eat early - then you have an empty night in your cheap Santa Rosa hotel room. Instead we tasted wine at some Healdsburg locations downtown - there are some open until 6 or 7, and then we'd walk the square a little before a 7:30 dinner. If you go to the Williamson Winery tasting room, you can enjoy tastings paired with food!