While I like the ambiance of WL better than Contemporary, I would say with boys that young stay at the Cont. Besides what everyone else said.
1. you have a walkway right into MK. That's my favorite part.
2. hop on the monorail to Epcot and other monorail hotels.
3. request room on ground floor facing the playground area.
(just imagine sitting there having coffee on your patio, watching the boats go by, while your kids have fun on the playgym area, with them still in sight.
4. If your too tired to do anything at night, you can still watch the fireworks from the hotel. The views from atop of the contemp. are some of the best. I also thought that the views from the Contemp. boat ramp were pretty wonderful too.
5.Boat to FW for FREE nightly campfire and movie. (althought the sticks and marshmellows are sold for a minimal fee. Also at FW is the petting zoo, River country, hayrides, boat ride away (also just a boat ride away from WL).