We stayed at the Barcelo Maya Beach (part of the whole complex, but in the more affordable part) in 2011, and had a wonderful time there with our then DD6.
Kid's Club was very casual and you didn't have to reserve a spot or anything, just come and go as you like. DD6 loved the bungee jumping (which was more like slingshotting), marble diving at the pool, and did some crafts. The pool is enormous and great for kids. It's not deep (~4 ft) so there's no diving but fine for playing around in. If you have kids who don't swim, you might want to bring some floaties.
Over by the Palace is some good snorkeling. I saw a French Angel, sea turtles, stingrays, guitarfish, and lots of ones I couldn't name. The coral is pretty beat up and colorless but there were lots of fish.
Over by the Palace one day was a photographer who had a couple squirrel monkeys with him, and he took photos of DD6 with the monkeys on her shoulders, with the ocean in the background. A couple of my most favorite pictures ever!! So we ponied up the money (can't recall if it was $15 or $30) for the CD (not an instant thing - we had to catch the shuttle from the Beach to the Palace and find the Kodak kiosk someplace inside the Palace in the evening). I heard they also had a lion cub on a different day, but it was after we left the resort.
The food is fine. I wouldn't say it was amazing, but it was fine given that it was buffet food. Everybody can find something they like to eat.
We ended up doing two excursions (Xcaret and Aktun Chen; both were worth it) while there, but we would've been fine just hanging there too. It was a trip that was both relaxing and fun. I'd go back there except I dislike doing the same thing twice.
There is a mini golf course there that we did one evening. There's a shopping plaza area where vendors are selling their wares, and on the evening we went they were having a "fiesta" with a little singing and dancing, and the kids got to smash a pinata. DD6 had a ball.
I don't know anything about the DR Barcelo, but I appreciated the direct and short flight to Cancun. DR is just that much further to go for us so I'm not sure I see that in our future unless we move.