The JCC Baltimore in Park Heights must have changed since the time the previous person was there. They still close early for Sabbath but during the winter are open on Saturday nights from 7pm - 11pm (more than enough time for me). Also on Sundays they are open until 7pm. For a while the swim program was messed up but now it runs well and they have schedules everywhere. They have a cafe with some healthful items and great pizza. It's a nice place with friendly staff where everyone feels comfortable.
The quality of the Park Heights JCC (versus the Owings Mills one, about 20 minutes away) really depends on what you look to get out of it. Membership to the JCC gives you membership to both locations, which is nice. Both have pretty nice gyms, which is what I look for (the OM JCC gym is a bit better but Park Heights is fine). The problem isn't how nice they are, it's the moronic (and slackerish) hours. The gym closes at 530 on Friday, in preparation for Shabbat, which actually starts at sundown (meaning 3 hours after that, during the summer). Shabbat ends the next sundown, but still, the J stays closed Saturday night. And after being closed for all that time, they close at 230pm on Sundays, because "it's Sunday." This just flat out pisses me off. They close at 930 other days. Or maybe 9, I forget.
One huge plus of the Park Heights gym is they have racquetball courts. One minus though, is that they don't have an outdoor pool (OM has three).