We have two very large bradford pear trees with a lot of roots on top of the ground. How should we handle this and not upset the tree?

If you have 2 very large Bradfords you should consider pruning and or cableling,Bradfords are notorius for included bark and stem failure. As for the roots in my opinion a layer of app. 4 inches of mulch over the roots would be a good idea. Cutting the roots can lead to various infections. Usally roots(which grow in the path of least resistance) are on top becausw the soilo is to hard for them to grow as they should.