Invited to a party that isn't that formal, you may wear alternatives to tuxedos. Here are some tips.
Leather jacket, white dinner shirt, bow tie (colorful bow ties are great too), black skinny jeans and black leather shoes (perhaps more formal shoes, suede is fine too)
Chris Brown
Pink blazer, white shirt, bow tie or regular tie, black skinny jeans (could also work with chinos if it isn't formal) and formal shoes.
Bruno Mars
Black blazer,...