For the leafs you can buy a roll of liner, it kind of looks like garden edging. Where did you buy your polyurethane bushings from? Are you sure they weren't the greaseable kind of bushings (might not be polyurethane ones) either?
I've had rubber ones go bad within a few months, start squeaking and stuff like that. Switched to polyurethane ones and they were awesome.
Lifespan of polyurethane bushings are about five years, sometimes less, sometimes more depending on climate and use. Suspension design also greatly effects the lifespan. I'm assuming your talking about your Jeep, which has a modified suspension which is harder on the bushings, and think of all the crap those bushings get exposed to. Three years isn't that bad.