I have only been to SDQ once, so I cannot opine on it. GCM is a comfortable, safe, interesting place to explore, especially if you're only there for a few days. Moreover, it has a good island town feel, if a bit pricey and curt in parts. In contrast, Old SJU is quaint and enjoyable, but when I'm there (10 times so far) I can't shake the feeling that I'm in an industrial port. So, with all due respect to my SJU friends, I don't recommend going there for your long weekend. NAS also gets a thumbs down. I have been to NAS a few times and have yet to enjoy it. Same industrial feel. BZE is a possibility. Very tropical and primitive without being run down, and they're anglophones, if that matters. I recommend GCM. Whatever you decide, have fun!