If you can grab a lobster roll at the Portland lobster company, then do so. I vacationed to New England in July and their lobster roll was flippin fantastic. I'm drooling for it now.
Also, we stopped at ogunquit before hitting Portland, which was our main goal, fiancee and I would have rather spent more time in ogunquit. Neat little town. You can check out Marginal Way for a scenic walk while you are there.