No extreme hiking, no camping? There are several decent hotels in Kayenta.
On your way in, signs point to the Navajo National Monument, not far off the highway. There you'll find a handsome visitors' center (definitely worth a look) and a trailhead to Betatakin Overlook. It's only a mile's hike and fairly flat -- though if you're not accustomed to high altitude, you're about to find that an easy hike can take your breath away. Keep going. It's worth it. Betatakin is a spectacular 13th century cliff house of the ancient Anasazi. Younger, fitter people may want to walk over there. My estimate is that it will take at least half a day. Two other ancient ruins nearby are rarely seen by visitors. They're much farther and require much more climbing. My suggestion: if you're a true adventurer and must see Keet Seel, call first to clear permission and ask their opinion on how long it will take and where you can camp.