Selina Union Market proved to be a nearly perfect place for our short DC visit. You can't really beat the location; we were able to walk to everything we wanted to see — and found amazing food spots mere blocks from the hotel. The one thing I'd mention for folks is that it can be a little loud; there's a rooftop bar (that's fun!) that doesn't really seem to shut down until sometime between midnight and 1am; we didn't really mind, and even wound up on the rooftop at one point ourselves. It even has a decent co-working space, which proved handy on the couple days we were working remotely.
If someone hadn't pulled the fire alarm at 1am on the last night of our stay, this would have been a solid 5 star review from me.