My little guy is only 2 1/2. Of course he can't ride any of the "big" rides, but he loves Epcot! I know he gets in free, but when he turns three next year we definately won't consider Epcot a waste of money for him at all.
Some of his very favorite things at Epcot are:
-The Journey Into Your Imagination ride. He is NUTS about the upside down house. It always makes him giggle like crazy.
-The Living Seas. He could have spent hours and hours in there. He really likes fish and he was mesmerized watching them in the round tanks. And, Turtle Talk was a HUGE hit with him!
-Watching the performers in World Showcase. He especially loved the Chinese acrobats, the MoRockin' band in Morocco, and Off Kilter in Canada. He clapped and danced and really, really enjoyed himself at all of those performances. At all three, more people ended up watching him than the show!
-He was also fascinated by the 360 films like "O Canada" and "Wonders of China". He just kept saying, "Wow!"
-The Maelstrom boat ride in Norway. This one has always been a big hit!
-He even just really enjoyed watching the Fountain of Nations dance to the music and change color at night. It really is an impressive sight - all choreographed with beautiful colors and movement. It's one of the coolest things in all of Disney World.
-Eating dinner at Morocco and watching the belly dancer. What can I say, he's a boy . . .
-Playing in the jumping water fountain on the walkway between Future World and World Showcase and looking at the "upside down waterfall" outside the Imagination pavillion.
-And, on all four of his trips so far, hands down his very favorite thing in all of Disney World has been . . . Illuminations! He loves this show so much! It's always the absolute highlight of the trip for him!
Anyway, I know your boys are a little older, but I still think they would find plenty to interest them at Epcot! I actually think MGM has way less to offer very young ones than Epcot does.