I think the meals included stipulation is going to be limiting. I don't think this is very common in the US? And the places that do tend to have a meals included option are pricey. Like Blackberry Farm. Really, I think you'd be better off aiming for breakfast included and just doing whatever for lunch and dinner.
If meals included is an absolute must I recommend Cancun. Many all inclusive resorts on the beaches and you can take day trips to Mayan ruins. You can do the dolphin thing there too. Obviously the affordability of this is going to depend upon airfares from your local airport. But if you can get a great deal on the flight (or a package deal) the rest of the trip could be very affordable.
http://www.cheapcaribbean.com/Colorado in the summer is amazing and so is Vancouver Island. But Colorado will be flights + rental car and transportation to Vancouver Island would be even more involved since it you'd have a flight, then transport to the ferry, then ferry to where you are staying.
I've been wanting to loop around Colorado and hit the Four Corners area and see the ruins there. Maybe Denver - Vail - Telluride - Four Corners - sante fe - Colorado Springs -Denver.
Maybe look at this site for ideas? Your could get ideas for locales and then tailor the exact itinerary to your budget.
http://www.familygetaway.com/Or a cruise! Doesn't float my boat (ha ha) but it's easy and meals are included.
