My wife and I and my 17 year old son and his girlfriend are overwhelmed with the number of great Caribbean vacation opportunities. We are looking for somewhere to go this summer that is mid-range in price, (maybe all-inclusive) on a beautiful beach with lots of things for the kids to do. What is your best recommendation?

Where are you from and what is your budget? How long will you be staying?

Vancouver. 7 - 10 days. $200 - $250 per night.

Is that price range per couple or for both? And not including airfare? And in Canadian dollars or US?

If for both couples and in Canadian dollars, I don't think there's a single place in the Caribbean you could go for that price at an AI rate, unfortunately. The least expensive places in the Caribbean are going to be package deals to AIs in Jamaica and Dominican Republic, about which I know next to nothing. Sorry!

I have to agree with ej. I can't think of anything it that price range. Holiday Inn Sunspree's are affordable but not the "best". They have one in Montego Bay Jamaica, Aruba and the Bahamas I believe.

look into Aruba, Playa del Carmen or Cancun MX.
Moon Palace AI Cancun.
Iberostar or Royal Resort in Playa DC
also check out the Occidental AI Aruba or HI & La Cabana Aruba those will be your best bets for mid range prices and great beaches with plenty of activities.
I wouldn't suggest DR with 17 yr olds, the resort costs are very cheap but you will be restricted to your resort, a 17 year old may become bored in the DR. they will love Aruba or MX.
MX is cheaper.