I'd much rather be in a suite or regular hotel than a B&B. As my FI likes to put it, "B&Bs are the picnics of lodging - they sound really romantic, but you inevitably end up with people stepping on your blanket and ants in your
food."
That aside, we went to Napa about two years ago for a long weekend and had one of the best trips of my life. We stayed at the Meritage Resort and Spa and it was PERFECT. It's south of Napa and out in the middle of vinyards.
They have a wine cellar, bocce court and hot tub that are all very worth-while and they run a shuttle into Napa itself, so we just parked our rental car once we got there. They also had an amazing concierge who hooked us up with the best driver
ever. (KEY when you're doing wine tastings in Napa as it is no fun fighting out DUI to begin with and in Napa, there are nine different jurisdictions, which makes it less fun). He knew all of the free vinyards, took us there for tastings
and stopped so we could load up with snacks so we wouldn't be drinking all day on an empty stomach.
The whole trip was really fun and really romantic and it puts a smile on my face just thinking about it. You guys will have a blast, no matter where you stay!