Some other suggestions might be the Schwinn "Japanamount" frames, Paramounts built by Panasonic. Very nice, generally lack the luster of the earlier US built paramounts. Can be had cheep. Panasonic also built some decent frames, DX's. 1000 was the lowest and 5000 the highest, I think, very nice.

Look for tubing stickers. Ishiwata, Reynolds, Tange (esp the "1" tubing), Columbus, Vitus. Look for double butted steel. Stickers aren't always there, but they often enough are.

Keep in mind there are exceptions to nearly every "rule" we propose here. Good frames are sufficently varied in little construction elements that there are exceptions to everything. I can think of quality frames without lugging, without derailleur hangers, without fancy lugs, whatever. But Lugged, db steel is a good starting point.