I give yogurt drops too but they love you when you have worms. You havent experienced bliss until you have 7 sugar gliders scrambling all over you. lol
I try to feed treats very, very sparingly as I don't believe they need it.
Lately, the treat though is worms -- which they get a few of most days. On occasion I will feed dried fruit. And when they go to the vet, they get yoggies.
I give mine dried papya and dried apple slices that i get from petsmart. There really for hamsters and other critters like that, but there safe for suggies and mine seem to love them. :)