We LOVE our Wii. My boys are 5 and 3 and can play the WII Sports games very well. We also have WII Play and WII Playground. All are non-violent, very fun games for the whole family. Your boys should have a great time with any of these games. We don't have it, but there's also one for babies (can ya believe it!).
For your older boy, try Super Mario Galaxy or any of the Lego games (Star Wars, Batman, etc.) While you do have "battles" on them, all the characters are made out of Legos and just fall apart and go right back together. No blood or other icky stuff.
A lot of times you can find older WII games in the clearance bin at Wal-Mart or on ebay. I also found a nunchuck that was compatible with the WII system for 15.00 at Best Buy. Sometimes you can also find the WII Play bundle that includes the game and a remote for 49.99.
Hope this helps. Happy gaming!
K. in GA