August is blueberry picking time in Maine. The Bangor State Fair runs from the end of July to the beginning of August and is the largest state fair in Maine. Sailing, whale watching, and all kinds of cruises are in full swing. Premium spots fill up fast that time of year as it's a short season. Many locals head out during August before the kids head back to school.
September is the start of fair season in MA. There are lot of small fairs-some are just town-wide events such as Yankee Doodle Weekend right here in Billerica but are well worth the time. September is also apple picking season. NOTHING beats a Massachusetts Macintosh right off the tree! Labor Day weekend is a very popular weekend for camping so you might want to consider reservations somewhere. After that the kids are all in school so there's usually no problem getting a spot. The north shore towns of Gloucester, Rockport and Newburyport are just about perfect in September. Still lots of water-based activities, shopping, fairs and street festivals going on.