Cocky / funny lines for wearing a suit
Well, you could just be wearing a jacket and tie, but most people you meet will call it a suit. Because few guys wear them anymore, let alone to a dance club, the girls who take a liking to you will come up and ask you, "Why are you wearing a suit?" while smiling and stroking your jacket sleeve or your tie. Since this is a form of shit-testing, do not give logical answers like "I dunno, I just think guys don't put much effort into how they look anymore, and I'm trying to change that." Bzzt! And definitely do not respond with, "Oh, do you like it?"
The response I go with is a template adapted to the context: "My _____ are at the dry cleaners, and this is all I could scrounge together." At '80s night, "My cut-off jean shorts and headband are at the dry cleaners..." At a lingerie / fetish-themed night, "My leather chaps are at the dry cleaners..." At the teen dance club, "My awesome Hollister shirt is at the dry cleaners..." If I went to bars or clubs that catered to 30 year-olds, "My striped shirt and jeans are at the dry cleaners..." You get the idea. Use a slow, unrehearsed, dry delivery, and you're guaranteed to tickle her and produce some genuine giggling.
In your line, try not to bust on what other guys are wearing, though, since that makes it look like you think they pose a threat, which 99% of them do not. That's why I prefer going to venues where wearing a jacket and tie would be more unexpected: then you're just commenting on the silly requirements that '80s night or lingerie night makes on people, rather than taking pot shots at other males.