K.G.
skateland is fun. Mom even can skate. With the new play area and things it can be a bit hectic so team up with another mom so you can keep track of the kids a little easier because spring break time is more crazy than usual.
sleep over with friends in the back yard.
i agree with the bowling- in gradeschool my boys even joined a summer league. with bumper bowling it makes it fun for 3 &5 yr olds too.
make a game of spring cleaning. I know it sounds nuts but kids like to be productive and show off their handywork. Doesnt have to be anything grand or perfect.
I know my boys enjoyed learning where spring cleaning came from and it helped them appriciate what we have now days compared. tell them as they say in the movie "Hope Floats" gotta shake the stink off!
good luck and keep enjoying those boys. Mine are 18 & 20 now and I dont regreat one single moment I spent with them instead of doing something else.