bookit.com good reviews Secrets Maroma and Dreams Cabo for AI for me.If budget is good Ritz Cancun or Capella Pedregal Cabo a tonne better.

Both Cancun and Cabo San Lucas are equally safe for tourist travel.

Because you specifically want an All-Inclusive I'd look at Cancun first. Although there are some available, they really aren't "the thing" in Cabo. People there more tend to stay at regular hotels and resorts and eat and drink out around downtown and on Medano Beach.

I've stayed at the AI Beach Palace in Cancun. The service we (a group of 12, ages 4-68) received was top notch. I found the food very good in all of their restaurants and their beach nice; can't speak for the golfing or nightlife (we were travelling with children).

The only AI I've done in Cabo was at the Villa Del Palmar, and I would strongly suggest NOT doing the AI for a multitude of reasons.

I've decided on Cancun and narrowed my decision down to Riu Las Americas, The Royal, and Live Aqua. Help please!!

Have you looked at the many AI resorts south of Cancun along the Riviera Maya/Playa del Carmen area? Much nicer atmosphere than the very concrete Cancun.

Schmerl,
No. Any resort recommendations? How far is this area from concrete Cancun?

The Riviera Maya is a big area.
Are you looking for adults only or family resorts?
We love the Ibeorstar Paraiso complex. They have family and adults only resorts and are about 25 minutes from Cancun airport and 20 minutes from Playa del Carmen. There are loads of activities there.
Again...depending on your budget and whether you want adults only, we can give more recommendatons.
It is just a much more relaxed atmosphere than being right in Cancun.

Can we expect a lot of college students on spring break in mid March?

Depends where you stay. Usually partying college students pick the lower-end AI resorts. I don't know of any destination in Mexico where college students totally take over a town.

We stayed at the Crown Club Paradise and couldn't have been happier with it. The restaurants were amazing. They have 24 hour room service so we would fill out a menu and leave it on our door the night before and they would serve us our breakfast at the time we requested it. The HUGE buffet that was open all day was INCREDIBLE and had so many food options that you couldn't get sick of. Every day you would choose a restaurant and make reservations in advance and go there at your given time, it was so good. There was Sea Food, Chinese, Italian, American (steak place) restaurants and a few more.

You might want to look at El Cid Marina Resort and Spa in Puerto Morelos, about 20-25 min from the airport, and the same from Cancun. What is nice about this resort is that they have a private beach, so there are no people selling you any wares. We thought the food was very good, there is a coffee bar in the lobby for a morning pick me up, there is an adults-only section, and a kids' area. We used bookit.com and were somehow upgraded (I think) to a top floor room with a jacuzzi tub in the room, and a hot tub on the deck!!! It was $109 pp per night, and our kid stayed & played for free. I would definitely return, and we almost never say that, since we like to try new places!

I've never stayed at an all inclusive, but if I did, the Aqua in Cancun looks very nice.