Personally, I'd stick with the 18-55 IS until you can get something much better and consider what you're missing in a second lens.
I agree. Stick with that lens until you can afford a real upgrade to something like the 17-40 f/4L, which can be had on the used market for $550 if you look hard enough. That was my walkaround on my 10D for a long time, and it never disappointed.
Anything between your current lens and the 17-40 will be a minor upgrade and, IMHO, not worth the money; saving up and moving to the 17-40 will get you into a much higher class in pure IQ terms.
If it's the reach of the 18-55 that's bothering you, again I would suggest saving up for something a lot better, rather than buying the 17-85. What about a fast prime like the 85/1.8 or the 100/2? Both are great lenses.
You're not going to find a really good lens with a huge zoom range. If you mainly use wide/normal focal length, save for the 17-40. If you mainly use (or want to use) longer focal lengths, get the 85/1.8, 100/2, or save for the 70-200 f/4L. Dont buy cheap glass; you'll regret it later.