Welcome to Lost. Lots of reading to do here. I recommend starting with this:
viewtopic.php?f=88&t=79401Anyways, I'll give a quick run down on our KKs for ya. I know you're not ready to lift yet, but.... Max lift is going to be about 4", anything after 3.5" is going to need aftermarket upper control arms. General consensus is to avoid spacer lifts, they tend to kill the front ends on our Jeeps. Some lifts will level you out, others keep a rake (we can address this when the time comes). Most will run 31s, so 245/75-16 or 265/70-16 with 2.5-3.5" of lift. At 3.5-4" you'll start seeing 32s (235/85-16 or 265/75-16), but then you start needing to regear to either 4.10s or 4.56s depending on where you live and if you tow, etc. Otherwise you lose a ton of power and gas mileage and start hurting the drivetrain from additional stress.
Wheel wise, 16s are the safe limit. Stock height needs to basically stay close to stock specs. Some people run 15" rims, but you need a stupid amount of backspacing for them to fit right, and at that point you push the tires out too far and cause quite a bit of rubbing. Largest tire size at stock height is going to be 245/70-16, some have rubbed with these, but it's an easy fix.
As AtTheHelm said you can level it out with 1/4" spacer plates and maybe a clevis. You could sneak a little lift out of her without the wife knowing and for pretty cheap if you want

Figure the clevis and plates will get you about 1" maybe a tad more in front. Should level you out, if you're nose high we can add a spring isolator to the rear for 1/2" of lift in back.
Btw, post some pics of the KK....the YJ and maybe WJ too.