XJ Jeep spring replacement. Is it necessary?

I got a question for anyone with some XJ insight.

I just got a nice '96 green 2-dr, 5 speed w/ 145,000 mi. on it, and I
want to do some repairs and add some mods to it before I put it on the
road as a daily driver, as a replacement for my civic.

As is, I can't even ride in it because the suspension is so bad! It
hurts the back, and is also dangerous.

The vehicle has also never had a wheel upgrade, so this is one
definite immediate must for better handling performance (should I try
to go 16" or + or just upgrade to some nicer stock aluminum 15"
cherokee wheels with 235/70/15's or whatever?)
My MAIN question is, however, the suspension.
Should I just put nice new shocks all around and a simple add a leaf
in back, and can I then still count on some good road handling and
cornering, or should I most likely replace all springs too??
I know the condition of the springs could determine this answer, but
I'm sort of looking for a simple answer for a light duty, good
condition, city Cherokee..

Anyway, anone get my drift?? I want to do it good! Somebody was
saying go Old Man Emu also. A local 4x4 center here in Mass told me,
however, that at higher road speeds it wasn't a great handler, and is
better known for a soft feel.

I like to have both: High speed performance handling, along with a
cush, comfy ride when rolling through the multitude of potholes that I
hit daily driving in Boston!
OK, I'll leave it at that..
or how bout Rubicon Express?? BDS?, I don't know!?! I guess I need
more advice.
peace, thank you, Ben