Everyone here has great recommendations. One place you will see a real difference is tailoring. If you are not built like a Russian supermodel, you need tailoring. This is where Marios really makes a difference. They will rebuild your suit so that it looks like it was made for you. What nordroms does is fine if you just need your pants shortened. Otherwise, go to marios.
Call right away and find out about upcoming sales. (it may be the winter sale right now) and buy when its cheaper. I try to stay in the Boss department both for price and style. You should be able to get a more stylish suit than at nordstrom, for not much more. It is your wedding, after all. No one under the age of 60 should be married in a brooks brothers suit.