We are coordinating with a few other families for spring break 2016 and are looking at either the East Coast of Mexico (Cancun, etc) or an island in the Caribbean. Looking for an all-inclusive that has a nice beach, good swimming from bach/pools, great service, good food (if possible), activities (do not all need to be guided at all) and clean rooms. Our family of 4 willing to pay $5,000 for 5 nights (adding air to this). Happy to share room or have adjoining rooms -- it does not matter. My first all-inclusive was a Spanish brand in the DR and it was amazing because more relaxed and yet gorgeous. Open to ideas! Thanks

Before you make plans for a vacation including the beach in that part of the Mexican world, better take a good look at the seaweed problem to see of it's gotten better and is going to continue to do so over the winter and into the spring.

I strongly recommend one of the Royal Resort facilities, especially The Royal Sands http://www.royalresorts.com/
We bought timeshares there when our 3 teens were in Middle school, and we have gone back tons of times, the teen always bugging us 'When are we going back?" Even though the main focus of the facilities is to timeshare owners, plenty of space is available for partial week renters, and I guarantee you will be treated well. No services are split between owner sand renters . . . you be treated like you own the place. - dg

Look into the Iberostar Paraiso complex or the Iberostar Tucan/Quetal. Both are in the Riviera Maya and are between Cancun and Playa del Carmen. The IB Paraiso has four family resorts....the IB Beach/Del Mar which share all facilities and the IB Lindo/Maya which share most facilities and also have use of all the facilities at the Del Mar/Beach. Great big beach and fantastic pools. Service is also wonderful.
Lots of activities or you can just chill out.
If you want snorkeling right from the resort, look into the Barceló Maya complex.

Look into Isla Mujeres. North Beach has been seaweed free (most of the problems with sargassum are on east facing beaches). Not too many AIs but that 5 mile long island has over 130 restaurants in all price ranges.
You might want to rent a couple of condos at Ixchel or Nautibeach, or look at Privileges Alux, they have an optional AI plan which you could do for all or part of your stay - otherwise breakfast is normally included. They often have Internet sales on Thursday am.

I second Isla Mujeres. The island is easily accessible and completely safe (20 min from Cancun). The beaches are beautiful and there is plenty to do. There are so many great restaurants and bars on the island that it almost seems a waste to do an AI. However, if you choose your best bet is Privilege Aluxes. The hotel is located right on Playa Norte, so you will be within walking distance to everything, and the teenagers can safely walk around the island without supervision.