You must consider where you are upgrading to. Lets start with wood types. Do you know if you prefer the full sound of maple, the focussed sound of birch, the middle ground of the poplar export you're playing, or do you have blend of woods that you like the sound of. This is the most important thing as it will determine the sound of your next kit and you want to ensure you're gona be happy with it.
Check out this page Drum Woods
for a run down on different wood types, then, go to your local store and try the crap out of the different kits. You should quickly get a feel for what you like in a kit. Do not be swayed by the sales people or the look of drum kits. You need to gauge the woods before making any other decisions.
If you look around the linked site, you'll find lots of information regarding the choosing of drums. Good luck and keep us posted.