assuming you don;t want to drop a grand on an occasional tux - I got one at Jos A Bank a few months ago. Very light weight, very comfortable, very traditional, $800 plus all the accessories, salesman dropped the price, out the door on everything for $450 (tux, shirt, stud set, suspenders, cumberbun, bow tie. The accessories are outrageously priced. the salesmen there are pretty cool if you get the right one, and will usually make a deal).
Then go to Bank. The cheapest one is barely above rental grade, was like $225 I think. The next one up is great. I paid around $300. Like everything there, regular price is absurd, but they'll always give you a sale price. If you go to the one downtown, ask for Hampton. He knows his shite. There is also a slightly heavy slightly set dark complected guy. He doesn't know shite. Avoid him like the plague.