I have not been myself (surprisingly little experience in Alexandria over the years despite living in both DC and Fairfax for most of my life). However, I have a buddy who lives around there and has been. He tells me it's a good place. He used to go there a decent amount before the pandemic. Says he hasn't had the steak, but his ladyfriend did and really enjoyed it. My friend, on the other hand, raves about the bar. As for atmosphere, he says it's sort of between casual and fancy with many people wearing kind of a business casual-type attire. I would guess slacks or nice jeans with a button down shirt will get the job done.
Sounds like a nice time. Enjoy!