Yeah I would suggest a 2.5" lift with 31's. I got a 4" lift on mine and I have 31's too, and it doesn't look as good as I hoped. The lift is good though. I would suggest Rough Country. That's what I have on mine. TJ's don't have leaf springs though, do they?
I got a 99 TJ back in sept ... I have been wanting a TJ since they came out. My wife loves it and I know I would but I didnt know I would love it this much I have 31inch tires and need a lift ... well, dont NEED a lift but I would really like about 2 and a half inches.