There is a reason that nearly all travelers to Jordan go to Petra: the scale and setting are beyond anything pictures can convey. Descending down the siq to the opening at the Treasury (Al-Khazneh) is only the beginning. Beyond the main road running through Wadi Musa are many other sites in the surrounding area.
The best advice we received (and followed) is to plan your trip to Petra: because there is so much to see, and the area is somewhat spread out, a little time with a guidebook goes a long way. We were prepared for lots of hiking: we wore trail shoes and prepared for lots of stairs. Most of the people don’t wander much beyond the central area, so it is easy to get out of the crowds by exploring other spots. And, avoid the weekends (Friday and Saturday), when it is most busy.
We arrived mid-afternoon on Saturday, and seemed to be the only people going in, while the majority of the traffic was headed back towards the entrance. Our goal was to head straight for the Monastery (Al-Deir) to catch monument in the late afternoon light. There were very few people here – even many of the trailside vendors had closed up for the night. We carried headlamps just in case night fell before we got back to the gate. When we returned, the central area was all but empty, reaching the entrance at twilight.
We stayed at My Home Petra, far enough from Petra’s entrance to avoid crowds, but easily accessible by walking or a 5 dinar cab ride. We walked to the Petra entrance (downhill), but took a cab ride back (uphill). The manager provided good trip planning assistance, and arranged a boxed lunch, ready for an early departure.