I have been to Gin Mill many times over the years. Just a small dive bar. They usually have live music and the upstairs roof is an excellent spot to hang out.
There are drink specials every night. They have a ton of dart boards....Gin Mill is actually our go to place for darts as there are plenty of boards and rarely ever filled. They also have a table top shuffle board (I believe it costs $1).
Casual atmosphere with a large variety of people and ages as patrons.
Pro Tip- Free popcorn