Hey man, I've been in mexico since Sep. 23rd, and I'm expected to stay a full 3 months.
Honestly, it depends where you go but even cancun is pretty quiet at this time of year. If your booking mid dec-end of march, stay out of cancun because the parties will be there.
Cozumel is a very chill island that caters (mainly) to cruise go-ers however, it is still a really relaxed place to be. No matter where you go (even downtown) you won't find too many rowdy crowds (if any).
Akumel, like jutes said, is an extremely calm place but I'm not sure if YOU & wifey want to go out at night time. The akumel life isn't very huge, but if it's all about the kids & you enjoy privacy, there are beaches in akumel that you may be the ONLY people there. Also, if you decide to visit akumel, PM me and I can show you an unmarked senote (hole in the ground you can jump into and land in fresh seawater connected to divers caves {i hope that made sense, I've been drinking brandy since noon})
Playa is less of a party but there are a lot of females dogs. 8:1 ratio at this time of the year.
in between playa and cancun is a resort, a place where you never have to leave. 12+ bars, dozens of shops, nice beach etc. just no town to discover (and if you don't want to explore this place is for you)
mmm merida is also a cool part of mexico, but you won't really have any close beaches.
So what EXACTLY are you looking for? I should be able to point you in the right direction (as long as it's EAST mexico)
P.S. barcelo (barcelo tucancun) is an adults only place now. (Basically singles go there to Phhhhu*k)
The other barcelos are decent, but again it depends what EXACTLY you're looking for.
Also check out trip advisor (
www.tripadvisor.com), and read reviews about the hotels & things to do/places to eat. really helpful site if you spend long enough researching.
P.P.S.
There are many hotels in cancun which offer similar to what dudekeith described. PM me if you have any other questions