I'm all too familiar with that fungal rash on the hip. I keep some clotrimazole ointment (non-prescription) on hand. If it catch it early, it is gone in a day.
As for the thighs, for me, it is often two things. First, I need to be less obsessive about fastening the bottom tapes so tight. It feels good, but doesn't really prevent leaks. Second, if I move the tape up slightly, a wider band of material will be pulled tight, rather than fastening right on the edge where it will cut into my thigh. Of course, as Bettypooh says, switching diaper styles often helps too.
-boogles