Congratulations on the wedding!
I agree with the others. And don't get too stressed out about it, there is always going to be someone who is 'maxed out', but for the most part it is a "quiet elegance" mix. Some of the men do wear tux but on our trips it seems more of the men wore a dark suit for formal nights, so either is fine. I would not go out and buy a tux just for the trip, a black suit will be very acceptable. Check out the links suggested, the tips and advice on this site are great.
Have a wonderfu wedding day and a great honeymoon.