Resorts
It isn't in Upper Michigan, but take a look at Sunrise Lodge in Land O' Lakes. VERY family oriented and fun. Nice beach, huge lake, etc etc. Also I dont know the name of it, but there is a newer lodge resort kind of place in Eagle River. Nice place. Pretty pricey. Here in the Marquette Michigan area, I can't think of too many places like that to go with family that is a RESORT type atmosphere.