Congrats on your impending nuptials! I’m going to work off the assumption that you’re willing to buy, yes? It is your wedding after all, and besides, we all know how I feel about renting a tuxedo (if you don’t, read all about it here)…suffice it to say, I feel bad things about the idea. Very bad things.
As for your assertion that tuxes don’t need to be formal, I feel like maybe you mean they should be more…accessible? Because I agree that some guys are scared off by tuxes, thinking they look like a) they’re wearing a “James Bond” halloween costume or b) they’re headed to senior prom all over again (it’s an unequivocal fact that all guys looked terrible in their tuxes at prom – you haven’t grown into your body yet, you’re definitely renting, and you know nothing about style…yet. It’s cool; girls cringe when looking back on their sherbet-colored sparkly dress / ringlet curl updo atrocities too). Thankfully, they don’t have to – and picking your own goes a long way towards a guy feeling comfortable in formal wear.
But make no mistake, a tux IS formal, and is best reserved for an occasion that takes place after 6pm (it is called evening wear for a reason) where guests are asked to dress up accordingly. As such, I’m going to make (another) assumption that you’re not getting married on the beach at, like, two in the afternoon. Yes? Yes. Moving on.
For a modern classic look, I’d recommend going single-breasted (the only guy I’ve seen who can get away with a double-breasted tux is Prince William and even then..I mean, he is a prince), single button, a shawl lapel with a bow tie or a slim peak lapel with a bow tie or long tie. Now, before anyone gets all scoffy about long ties with tuxedos, let me say one thing. Sure, it’s not super-traditional, but I don’t think it ruins a tux. You know what I think ruins a tux? Tugging at your bow tie because you feel uncomfortable or not like yourself in it. Try both, and go with what works for you.
If you can stand it, I’d push for midnight blue over black, as it can look better in pictures than black. Remember the tux Paul Rudd wore for his wedding in I Love You, Man? He looked super sharp, right?!
As for WHERE to get it, you have a few options depending on your price point. Brooks Brothers can get you suited up, and is a great end-to-end solution, with plenty of shirts, ties and accessories to choose from. However, you might find yourself fighting with their tailor to get the suit as slim as it sounds like you prefer to wear yours. Suitsupply is also fast becoming my go-to recco for affordable-but-nice suits. And the tailors there understand a younger man’s aesthetic better, so when you say Thom Browne, they hopefully won’t shake their heads dismissively and try to back you into loads of pleats and a boxy jacket.
If you have the time, money and druthers, I’d say it would be great to go made-to-measure. A service like 9tailors, MyTailor.com, or Evolution of Style can get you (and your groomsmen) suited up and looking sharp for your big day.
French cuffs and a pair of badass velvet slippers complete the look. Good luck!