Non-traditional Menswear?

If it's super casual, what about just dress slacks and a nice button up?

Nice pants, button down shirt and a vest with tie?

edited: the tie can come off for reception (same with vest) but will give some nice pictures

I agree with Jet.

Have you and FH Googled and Pinterested together?

Regarding theme, have you looked at Offbeat Bride?

I agree with Jet also. That's the look FH is doing & I think it looks great!

The above points about a vest/pants combo can be a good compromise. We're in the formal wear business, so my bias is toward a dressier look. That said, maybe your FH is just not into what he thinks of as a traditional tux or business suit. Here's a lighter combination that we've done for a number of summer weddings that might be an option. You can make it more formal with a vest and tie or less formal with just an open collar white shirt. I've also seen some very nice seersucker suits for a Cape Cod themed wedding (that may fit your vintage ideas, but may require some selling if he's not a suit guy). Check with a locally owned tux shop for options on a suit rental. The larger chains generally don't rent suits, as they'd rather have you buy one instead.

Thanks everyone! He says he wants to wear suspenders. I'm ok with that. I just want everyone's pants to match.

We are not doing tuxes either. i actually don't like them. so we are going to get tan suits where the men can rent or buy to go with our navy and blush theme.

Our groomsmen and FH are all going to be in simple summer kilts with cream shirts