Advice on Cancun - What area to stay in?

I've been wanting to take a vacation in Cancun for a while now and
we're
seriously considering it for a week in May. We went to an
all-inclusive
resort in the Dominican Republic and it was fantastic. We had a great
time!
So we're looking at some AI resorts in Cancun. But our first decision
is
what area to stay in. I've been reading up on the web but I'm still
not
sure about the areas:

- Cancun pennisula itself - I read that this is pretty wild, maybe too
wild
and crowded for us I'm not sure. I know it's resorts squeezed next to
each
other and stuff. The city is not far away, as well as Chitzen Iza
(I've
been there once while on vacation in Cozumel and I really enjoyed it,
I'd
like my wife to see it as well.)

- Playa del Carmen - From what I've read this is a fast growing city
south
of Cancun. My question here is : Is there enough to do in the city or
would
be travel to Cancun? We like to eat, shop, and just walk around and
take
pictures.

- Even further south than Playa del Carmen - Some of the nicest AI
resorts
are here, but it's far from any city.

Is it worth going into Cancun several times or is once enough for a 1
week
trip?

Thanks for any advice you may have.

Michael
--multiplaza.nl.nu--