I want to plant some trees in my front yard, but I need help deciding what kind to put in. Pictured is my yard currently. I'd like to put up a short fence by the sidewalk (to continue the stone fence that is already there) and then put three trees for a little more privacy and added beauty. I don't have any idea what would fit or look nice there though, and I need some help.
-zone 5
-I don't want a hedge, I would like trees.
-The trees need to be low maintenance.
-NO SPIKEY BALLS. That's what the existing trees drop and I hate it. No "conkers".
-If they have berries or fruits they need to be safe for kids.
-I would prefer that they don't send off a ton of suckers (I think that is what they are called, the little seedlings that I would have to go pull every year.)

I don't even know if such trees exist, but I would really appreciate your help trying to find something close.