Even though wine tasting is just "tasting" and even though it only happens during the daylight hours, TONS of people get DUIs coming back from a day in Solvang. So sober up before you head back. A good idea is to go to faraway wineries along 154 first and taste lightly if at all, then park in solvang and walk around to other wineries and dinner. that way the driver can actually do a tasting and spend some time sobering up and eating something before the group heads back. (of course, a designated driver is ideal but if you are a couple etc this is a good solution too)
Please be forewarned that cab fare is $10 to start and $3 per mile ~ which adds up quickly in the Santa Ynez Valley. The owners of Solvang Taxi are very nice but the price can be shocking at your destination if you are not prepared.
Every hotel in the Santa Ynez Valley is usually sold out by midday on Saturday if not sooner. Most of the nicer hotels require a two night minimum stay on the weekends as well. Be sure to reserve at least a month or two ahead for holiday stays as well. Advance reservations are recommended for best rate and room choices.
When driving in Solvang watch out for the trees.... I like the idea that they have built around them and are keeping the old trees around.