Oh, this is a good question. I will be watching this thread!
Missy, my boys nap quite a bit. But, they also enjoy running from one end of the house to the other, several (a dozen?) times a day. This is because if they hear someone outside, walking by, they'll want to go outside (through the dog door, in the back of the house) to check it out, and then they'll want to race to the front window to check it out again from another angle. When one runs, the other will run too, so they don't miss out on any action.
My house is long, from front to back, which bothered me until I realized it is the perfect Hav indoor dog run.
They romp wildly (bitey face, clash of the titans, etc.) and do RLH about 2-3 times a day, usually in the morning and before dinner, and if I've been gone awhile during the day, again when I return.
Scout will also play by himself, getting toys from the toy hut and rubbing his topknot out and his body all over my furniture.
Sometimes they play a little more too - depends on their moods!