Napa Tastings...no reservations needed?

We’re headed up to Napa this weekend with a bunch of friends, and our plans have altered slightly. Sunday was to be a half day of tasting, but has opened up and the group wants to try a hand at tasting all day. We have afternoon plans for tastings in Carneros/Sonoma (Adastra and Sojourn). Are there any reputable places we can drop by on Sunday morning? I was going to take the group to Heitz to try the port because reservations are not required there. It may be too late in the game to try to make appointments.

Thanks!

I don’t believe that many/most places along Highway 29 require reservations. Note that even though some of these make fine wine, the tasting room experience may not be all that fine, nor will you be necessarily drinking the winery’s best offering. (I am qualifying this by saying that I haven’t been a Highway 29 winery hopper for nearly 20 years. )

One more point - requiring appointments doesn’t necessarily mean exclusivity. It means they couldn’t get an “open to the public drop in” tasting room permit, which are quite restricted. Some smaller places welcome your “last minute” visits. They just can’t have an “open 10 to 5” sign out.