Yeah, FWIW, I've had jobs that caused me to buy a few suits. I like SD's tan linen suit idea for the wedding, but you'll get more use out of the navy suit over time. Go flat front, 2 button, IMO. No suit ever stays at the forefront of fashion, and pleats will return eventually, but this is still the better option now and probably more "timeless." What the suit is made from -- wool or cotton -- also gives you different looks. It pays to talk to a knowledgeable salesperson. And it'll need to be tailored to fit properly.
I've actually purchased suits from both Brooks Brothers and Jos A Banks, and I think the quality is pretty much the same, although it will definitely impress more people if your suit is Brooks Bros.
Shoe color? Make sure the shoes match the belt, but with a navy suit you could go black (more formal) or caramel brown, depending on the wedding:

And make sure the future wife signs off on your tie color; they tend to think that's an important detail. That's all I got.