We were there for the first time yesterday. I've found out that there's Salsa lessons and dance every Mon and Tue on Latin Dance web site. It said that Dan and Ann Roman are teaching beginner and intermediate classes from 7pm to 9pm, then DJ plays Salsa music.
We didn't see Ann, but Dan was there. We came at 8pm. There were a lot of people on the small dance floor. It was one hour starting with routine and finishing with a little nice combination. To my taste, there were too many people. The cover charge is 5$, cheap. Dan is a good man and teaches well. So, we'll definitely go there in the future. For those unlucky loners: Dan encourages to switch partners, so you'll have no problem to find a partner :)
Clarendon Grill is a bar. The staff is friendly, parking is free and enough. The bartender (nice guy) told us that Tuesdays are "slower" than Mondays, meaning "not that crowded". It was too packed right after the class, maybe everyone wanted to rehearse the moves :) After 10pm, it was easier to dance.