Originally posted by: Viper GTS
Clipless pedals are pretty near the top of my upgrade path, though I'm not sure how necessary they are for right now as most of my riding will be on pavement (90%+). I don't like the idea of tipping over on pavement either.

I suppose I could get used to the pedals in the grass first.

What other upgrades would you suggest after that? Clipless pedals are pretty cheap, so I can toss that in with the next item you'd recommend.
Clipless is pretty much a Good Thing(tm) across the board regardless of where you ride. You'll see what I mean once you try it out. Being able to pull up on the pedal as well as push down makes a big difference. As far as learning how to use them, just clip in and out a few times to get used to the feeling (kinda like a ski binding: step down to clip in and twist your heel out to clip out) and back the release tension off at first. Go for a few rides on back roads or in a park and practice stopping and clipping out. It will become second nature very quickly. It's actually much faster than a strap/cage setup once you're used to it. FWIW, tipping over at a stop is more embarassing than painful...you just sort of roll into a ball and end up with your bike half on top of you and a dozen or so laughing motorists. Just take a bow and keep going.
Other upgrades: Hmmm. Kind of a tough question. It depends on how much more loot you feeling like dropping.
Bar ends- I really like these for climbing or being a tad more "aero" on the road. They're kinda "out of fashion" right now, but I like 'em.
Saddle- Manufacturers often cut corners with the OEM saddle, knowing it will likely be replaced (saddles are very much a personal preference thing). Sounds like you and I are built similarly and I've been really happy with my Selle Italia Turbomatic. You'll have to experiment and see what fits your butt.
Derailleurs- An upgrade to LX or higher will give you crisper shifting and drop some weight as well. Not too expensive either.
Wheels/Tires- You'd be amazed at the difference a lighter wheelset makes as far as how the bike feels. Since they're rotational weight that you have to spin up to accellerate, taking some weight off here will make your bike feel snappier. You may want to go for some slick tires for road riding as well since the knobbies are heavy and add rolling resistance. A set of tires and light innertubes is also a fairly cheap upgrade.
Fausto