I'm assuming that the 11 day restriction is because you're still working, but you won't be forever.
This is just a suggestion. Figure out how far you can comfortably drive in a day. Let's say 400 miles. So, break out a map, draw a circle with a compass at 1200 miles. That becomes the area where you can drive 6 days and camp 5. There are a lot of places in that circle. Yellowstone, for instance. You can't see all of Yellowstone in depth in 5 days, but you can see where you'd like to re-visit. A 1200 mile circle would take you as far east as St. Louis, north and south, well into Canada and Mexico, and about half way to Hawaii going west.
Once you figure out the general area you're going to visit each trip, get on here and ask for suggestions. Somebody on this forum has been there - probably several. Adjust your circle for how long you like to drive in a day.