Four of us (two couples) spent 5 days in Boca Chica last March and thoroughly enjoyed ourselves. It is not a resort town in the sense that most people would think (no ritzy boutiques or trendy restaurants) but is fun and cheap. Additionally, the scuba diving is great (according to our divemaster who works in both the south, east and north, it is also the easiest location to dive due to currents/rough seas in the north and east). I believe the nightlife is varied - ranging from casinos, clubs and small watering holes but I have to confess that we spent most of our nights on Calle Duarte drinking Presidentes or cuba libres and talking to folks from around the world who were also visiting. There are a number of young women (and I mean YOUNG!) who are working as prostitutes and older men who are partaking of their services (along with skinny dogs about in the streets) so if that type of thing troubles you, I would suggest an AI. The prostitutes won't bother you unless you are a male and alone but you only need to tell one or two of them no, and the rest leave you alone - or as others have suggested - use the finger wag which is the universal signal for 'no thanks' understood by everyone in DR! The weekend on the beach is a sight to behold with all the families from SD enjoying themselves - blaring boomboxes, great street vendor food and plenty of lovin' going on! If folks are interested in visiting SD, Boca Chica is very convenient for heading into town for an afternoon.
I suppose it just depends on what each of you enjoy on whether you will enjoy Boca Chica or another location the best. You can find out more about Boca Chica at
www.bocachicabeach.net or check out my trip report at
http://dr1.com/forums/showthread.php?threadid=17580. There are definitely good and bad things about Boca Chica but as I said, I thoroughly enjoyed by time there. I haven't been to other beach locations in DR so can't really provide you with a comparison but it was by far my favorite beach vacation for a number of reasons.
I hope this reply was helpful - Susan