I have been really happy with aftermarket swaybars. Really leveled the truck through the turns and reduced roll, making aggressive turns more predictable. First I had an Addco, which I was very happy with. It was damaged in an accident, and I replaced it with a DJM bar. The DJM is even stiffer, which I love. People have also said good things about the hotchkis rear bars as well. Generally speaking, the front bar on our trucks is more than adequate. I just replaced the front bushings with urethane to increase its performance.
Oh and those mods you listed are the best bang for your buck. PCM4less Tune, shocks and struts, and it will be like driving a new vehicle.
Figure that'll set you back ~$200 by the time shipping is done or you do the core program. With the remaining $400, a set of Bilstein HDs all around for ~$240 is a good choice to really help the ride IF you plan to stay at stock height. If you plan to drop it or lift it, dont spend the $$ on Bilsteins. The fronts are good for stock or lifted, lowered there are much better options. Rears are only good for stock height.
If you're a member of TBSSOwners.com, Tony is doing a DJM rear swaybar group buy for $215 shipped. I have both the DJM and Hotchkis rear bars, the DJM one is stiffer and Im happy I bought it and left the Hotckis on my 02.