What city/area with chain hotels is good for a 5-night summer stay & is within a 12-hour drive from DC?

We have Marriott points. The points cost for 5 nights is the same as 4 nights, and we have enough points to stay at a not-very-fancy (but not lowest-point-level either) Marriott-brand hotel.

We live near Washington, DC and would be willing to drive anywhere within 12 hours. The trip would have to be in the summer because of our jobs. It would have to appeal to a teenager (our daughter) to some extent. And we might do an up-to-2-hour (each way) road trip one day to see something special, but we're not looking to do that more than one day.

Due to the cost of airline tickets, we're not currently considering places requiring flights. So we're looking at the US and Canada. Sorry, Mexico and the West, but you're just too far.

Thanks for any ideas. Even if we don't go this summer, I still like finding out about different places where I might go someday.