Both are pretty, meh.
You can probably sell the D80 + 18-135 and get a D90 body. The D90 body is pretty good. Always felt like the D80 wasn't as underdog as my D70s and nowhere near as good as my D300.
The 18-200, just do it. I've been running my 18-200 since the beginning of 2007. Except for photojournalism (used either a 17-35 or my 80-200) I use the 18-200 for EVERYTHING. Image quality is not as good as the 17-35 or the 80-200, but both of those lenses cost +$500 (each) over the 18-200 so it damn well should be better. Used to shoot magazine articles mainly using the 18-200 on a D300 body. For dynamic environments, its a great lens. You don't have time to dick around with changing lenses and you can't carry a second body, it just works. Great for wheeling.
Couple that with a SB-700, and a 50mm 1.8 (Its $100 bucks and helps you in low light, perfect? No but better than nothing) all in a LowePro Nova 2 camera bag and you've got a very good, capable, compact setup. Play around with CLS to add another dimension to your photography.