First, I agree with above, what do you wan't to do that you can't do stock? Now adjust until you can.
Second, I know this sounds dumb, but take a look at different google images of different set ups, and see how extreme or modest you want to go.
Here is the most organized comprehensive images I have seen posted elsewhere:
The Jeep LJ | Jeep TJ Lift Pics
Tire sizes range from anything from 30-40+" and lifts from 0-10+". There are also many ways to do a lift.
Suspension lifts are more costly, but provide the most performance out of a lift
Getting creative with combo lifts (BB and BL) and/or fender mods can be cheaper.
The cost of lifts is not linear with lift height. The higher you go, the more modifications that need to be done to do it right (regearing, SYE, axle swaps, welding, etc)