The seaside town of Bar Harbor, ME is surrounded by one of the most pet friendly National parks around. Spend your days exploring beautiful Acadia National Park and your evenings in pet friendly Bar Harbor. Check out @barharborcc for more on what makes this city great for pet travelers. (Photo credit: http://rhamphotheca.tumblr.com/post/32757033142/acadia-national-park-maine-usa-photo)
Horton Mill Covered Bridge...north of Oneonta, AL..It is 220 feet long and is the highest covered bridge over water in the U.S. It's right off of Highway 75--and you might want to check out the beautiful Palisades Park while you're in the vicinity.
"Free" Falls Park - Sioux Falls, South Dakota! Spend a day at the falls, climb rocks, go fishing, have a picnic, climb the tower, ride the trolley, roll down a grassy hill, you could even stay super late for the lazer light show after dark in the summer.