Bike riding/swimming vacation?

  I'm on the east coast, with a car and a bike, and a week to spare starting on Tuesday next. Looking for a place with (here's the kicker) with 1-week rentals available, relatively flat (for biking), and good swimming. Doesn't have to be salt water.
  I want to bike on country roads, do some writing and reading, maybe have a couple of friends join me from elsewhere on the east coast.
  Got any ideas? :-)