I do weights for muscle endurance, using a method that I devised myself. I'd like to share it with you, and if you ever wanted to give it a try, I'd really like to hear how you get along.
Any exercise you do, set the weight to about 60% what you would do if you were doing 3 sets of 8-10. Now you 'staircase' them: do 1 rep (easy, I know), then without replacing the weight/resting, take 5 breaths and then do 2 reps, another 5 breaths without rest, then 3 reps. You will do this all the way up to 10.
You will find this is very, very easy until you get to around 8, and then it is really, really hard. And that is the golden bit- the last 8, 9 and 10 when your muscles are already very tired. In total you'll do 55 reps, but for some reason it is much more tiring than doing 5 sets of 10 and then 1 set of 5. Weird.
As I mentioned, one of the key things is not to give yourself real rest. When I do situps, I do them with elevated knees so that my shins are parallel to the floor, and I don't bring my knees down between sets. That makes it stupidly harder. When I bench press I keep the weight pressed up between reps, I don't replace the bar (stupidly harder, again). For bicep curls, I don't put the dumbells down, and keep my grip tight on them (works the forearms more, but still much harder as a result). You get the idea.
A nice bonus about this method: you go on one piece of equipment once. If other people are in your gym, they can't use your equipment before you've finished a set.