IMO the tubing on a bike is just part of the overall quality spec. Since the frame is the central component, it's pretty important to get something decent if not high end. For example, if you look at the columbus charts, there's really very little difference between alle or cromor vs their high end internally splined stuff. Don't let seamed tubing bother you. So, I would seek out the high end stuff, but wouldn't shy away from Reynolds 501, Columbus cromor/alle, Tange 2, etc. Ishiwata 022 is also in that same league. Reynolds 531, Columbus SL/SLX, and possibly Tange 1 could be considered an upgrade from the first list, but only if you're a light and strong rider. The type of frame build will be more impactful than materials. That is, do you want a short wheelbase, steep steering, uber responsive crit bike; or a more relaxed rider like a trek 630. I guess in your situation I'd try to find something in the sporty if not racy category, as a tourer would have longer stays and feel more flexy under power. Seek out the mid/high side of good brands, as these sometimes come for fewer $'s (Univegas, Japan built Schwinns, Centurions, Fuji's, early specialized steel roadies, some of the 400-600 series
treks, etc).

Most of the sets listed within the table posted in this thread are nice riding if built up properly.
http://www.bikeforums.net/showthread...or-entire-bike


Think of less than uber high end tubing as a small compromise, and save your upgrade $'s for the right tires, brifters and a nice wheelset. Not that there's really any reason not to ride the snot out of it as is, before you upgrade anything. Maybe find a few examples and add to the thread in terms of "is this a good bike", not "is this worth the price". The ladder will probably get the thread moved to appraisal section. Good luck, have fun.