Thanks for the additional information.
The Rockies are beautiful that time of year. A trip through Yellowstone, the Grand Canyon, etc. is awe-inspiring.
If you like a little cooler weather late in the summer, the Pacific Northwest is the place to be. The Cascade mountains offer beautiful scenery and some climbing possibilites. Rogue River white water rafting in Oregon is another fun trip.
Have you thought of a horseback riding vacation in Wyoming or Montana? There are many family ranches that take in visitors and allow them to help with chores as well as getting to do plenty of trail riding, cookouts, etc. Here's just one of them:
I see you've been to Alaska and Puerto Rico. Hawaii is great if you love the outdoors. We especially loved Kauai for the beautiful scenery, while Maui has the best beaches, Lanai the most opulent resorts, and the Big Island has the active volcano, a huge variety from mountains to seashore, and lots of night life.
You can spend a month in Texas and not see it all. Be sure to check out the small towns as well as Dallas, Fort Worth, Austin (great music), and Houston.
A trip through Tennessee and Kentucky is beautiful, from Nashville through the bluegrass country. You can actually pet thoroughbreds at the Kentucky Horse Park in Lexington and nearby Berea has wonderful handcrafts.
One of our own favorite late-summer destinations is New England. From the ocean-viewing in Maine, the breath-taking mountains of New Hampshire and Vermont, the apples in upstate New York, there is always plenty to do.
Late summer in the mid-Atlantic is still plenty hot. Maryland,Virginia, and North and South Carolina all feature the Atlantic ocean on the east as well as the bays. Beach cottages and hotels on the ocean are popular into late September (rates drop after Labor Day) although ocean bathing gets a little cooler into October. The islands off South Carolina and Georgia all have beautiful beaches as well as resorts that range from family-friendly to truly opulent. Of course Florida has options for everyone from the beaches to Disney to horse racing and car racing.
New Orleans is still steamy in late August-September, but if you don't mind the heat, it's a fantastic vacation. Getting off the main roads into the bijou is especially interesting, although my personal preference is to visit in the cooler months. If you are a summer person, you should be fine anywhere in Louisiana, Alabama, Mississippi, or Georgia.
I hope this has given you a few places to think about for your vacation this year, and perhaps for some time in the future. For some of the places mentioned, it isn't a bad idea to make reservations several months in advance when your choice of dates is more open.