I can't begin to express my gratitude for the folks who take them, finding drunk drivers after the wineries close on the weekends in-season is pretty darn easy (and the Napa paper publishes the names of everyone convicted on a weekly basis)

I don't think the limo thing is always an anti-big group issue, sometimes it is just a parking issue, but either way once you get a list of places to see nailed down, it doesn't hurt to check online, ask the limo driver (if using a local *i.e., Napa, not bay area, company) or the concierge