1. Porcupine Rim was the best I rode. Spending $20 on a shuttle was money well spent, roughly $0.01 per vertical foot, or less. The option to go up to Kokopelli adds an extra bit of singletrack to the ride. When I heard parts were shared jeep trail, I thought "I guess that's OK". In reality the jeep track is sick. The singletrack at the bottom is epic. The Notch in the middle gives me nightmares. I'm afraid I might want to try it someday.
2.Slickrock is a blast and the trail head is inside of Sand Flats campground. I'm glad I didn't fall for the temptation to just ride this one for the whole vacation as good as it was.
3. Amassa Back. Somewhat like a Porcupine Rim Jr., but there is no shuttle available. Man up and grind the jeep trails to the top where there are some great singletrack trails. Or so I'm told. My derailleur caught a rock 3/4 of the way up and didn't work as well afterward. The snapped chain on the way back down was a bonus.
4. Take the bike insurance. Then nobody at the shop has to listen to your lame story about how the derailleur flipped into the spokes while you were "just riding along".