Men's attire

It can work, I found a picture on google ( I posted it below) but i think if they all wore the same tie it would look more uniform in pictures. Also, our men tried on everything including the vest and they just didn't like them so they just wore ties and I thought they looked so good. They looked so sharp! They said they felt like they were going to prom with vests haha. But it's all up to the guys and how they feel in it.

Depends how high the button stance is on the suit. If it's low, I think a vest and neck tie would look fine. A higher button stance and I would prefer a bow tie.

Edit: note the picture above posted by mimitrue. That's exactly what I meant.

If the weather is likely to be hot, don't make the guys wear vests.

At my beach weddings, guys in vests are only comfortable when the weather is cool.

We aren't doing tuxes, but FH is wearing a bow tie & His guys are wearing regular ties. It looks fine to mix and match.

Mixing matching will look good. I would say no to the vest - I always think it looks more like prom than a wedding.

All of the guys in our wedding are wearing vests. It's really a personal style option really. I like the way it looks and know that at the reception all of the coats will be coming off. I like the look of the vest without the coat rather than the shirt and tie only.