Do wine tasting/flights in DCA at the place next to Wine Country Trattoria. So fun! I prefer the port and chocolate tasting, but sadly that is gone. They may still have the port and cheese tasting but if not, they have other fun things.
Trader Sam's!! Get there near opening time (11:30, I think?), grab a table and have a blast! All drinks and appetizers I've had have been fabulous.
Napa Rose lounge! Have a wonderful dessert and coffee or a hot drink next to the fireplace. I LOVE the homemade hot chocolate, which is sooooo much more than it sounds. It's made from a melted premium chocolate bar and comes with 3 little bakery items made up fresh while you wait. Out of this world and only available in winter

If you want to spend the money, Napa Rose chef's counter is fantastic, too.
Maybe do a tour! Those can be a lot of fun. I've never done it, but you can hire a plaid to take you around for X number of hours. Lots of perks go along with it but again, it's very pricey.
Have a wonderful trip! Sorry my post is mainly about eating and drinking, LOL.