Hi Frank,
It's definitely worth a play!
Penobby is a very solid Ross course that has been recently (within the last 10 years) resto-vated. There are some that argue that the bunkers never had the frilly edges they do now, but I think those will soften over time. It's a pretty wide open mid-career Ross with a great variety of green contours. There are a couple bowl-shaped greens, a couple crowned, a couple tiered, etc.
I know you have no choice on the others...but I would rank PVCC ahead of both Sugarloaf (by a mile), and Belgrade (smaller gap). I haven't yet played Sunday River, but hope to remedy sometime soon.
Another idea would be Kebo Valley, about 90 minutes SE of Orono...doing both in a day would be possible, but that leaves you pretty out of the way at the end of a day, on either end...