If you were wondering – according to Emily Post (and we agree 100%), for gentleman guests white suit should be an option only in case of weddings in a tropical climate. The only other case we can think of is when you are invited as Elvis impersonator:)
Usually for formal weddings men are advised to choose a traditional dark suit.
If wedding is planned to be “laid-back” and informal, men can consider wearing light trousers and a dark blazer in the summer.