congrats on the engagement and welcome to the WS Boards, ALW.
For the salad, particularly since it is an engagement party, you'll want some sparkling wine. I've been drinking the Domaine Carneros Brut lately, and would think that would go nicely. (It's about $18 or so per bottle)
The sirloin: I'd suggest a cabernet. To keep the cost down, you might consider the Horse Heaven Hills Cab from Washington. Columbia Crest makes it I think. It's readily available and it's about $15 I think.
The chicken and the salmon: Generally, I like to pair a food that is cooked in wine with the same wine in which it is cooked.
The S. Florida folks might have some better ideas.