I am asking the same questions right now. I have a 3.5" RubiconExp kit with 30x9.5 BFGs. My leafs are a little saggy, so I wanna definitely add at least a small shackle for now. But I think I'm too cheap to lift the front more at this point because of how much extra crap goes into that. UCA's, better LCA's if you don't already have them, new track bar, brake lines, sway bar disco's if you don't already have them, and possible a transfer case drop if it gets vibes. In my opinion, that's a whole lotta money to only step up 1-1.5". I think I may just do about a .75" shackle in the rear for mine now, possibly a small TC drop, and then do some engine mods. As for yours, I don't know what kinda lift/components you have now, but if you have decent stuff on already, you could just go with a small (1 inch or less) spacer in the front and shackles in the back and probably be ok.