I think all three would be great choices for your needs, although I like the atmostphere better at Church and State and Rivera than I do at Casa, which has sort of a corporate-y feel. I also haven't tried the food at Casa since the chef change. The mixed drinks are better at Rivera, I think, but I loved the food at Chruch and State more (although I definitely enjoyed Rivera.
I've only been to Church & State, of those three, but I've been there twice and I can't wait to go back again. Definitely fun & hip (it's quite lively, or loud, depending on your point of view) and the food is excellent. I walk by Casa almost every day; I haven't been inspired to try it. As mentioned above, there's already been a change in chefs. The original menu just didn't seem that exciting to me. If I want tacos, I'll find a good truck or streetside table. You can't get steack frites or bouillabaise at a truck.