Well... you could go to Freeport and photograph the tourists going into LL Beans at sunrise and sunset!! They are open 24/7.
...orrrr... you could head up the coast a bit and try for the Damariscotta/ Pemiquid Point area. That area is really nice.
Personally, I think Portland is too crowded an area but it is all relative.
Any place along the coast on a small back road will give you some nice stuff.
If possible, buy the DeLorme Gazateer map book of Maine and it will give you every road you could want.