Hey welcome to one of the best bass fisheries around and lake Berryessa is no slouch in kicking out DD Largies as well as fat smallies and Spots (the trifecta)
The Vineyards are essentially the flats on the east side, as you have deduced looking at the map most guys would refer to the vineyards as from Gilly Canyon to Tully Canyon. This is essentially a large tapering flat that has small creek channels running through it along with rocks, trees, shrubs, old vines and vinyard posts etc... followed by a steep drop. The way i started breaking down this area is by using the old navionics and my eyes looking up on shore follow those creek channels down and intercept them on your graph. Pro Tip for this area bends and turns are high percentage, so is structure of any sort. Also a small depth change ie 1' -3' is a creek channel or depression and these fish can stack up in here. Especially in the spring and late winter. Once you get a feel for a creek channel follow it all the way out to the drop off and beyond i would say somewhere along that channel you'll find your school or at teh drop off itself. If all else fails just look at where the boats are parked

Seriously this a big flat and can be very intimidating an LV 500, or something that covers water is a great way to learn it IMHO once you find them fish your fish.
https://rbbassfishing.net/2013/01/15/la ... ort-11113/
Thanks for the post on Westernbass and let us know how you do!