Cava vs. Red Wine

[WitlessPagan]

My friend and I recently got in a debate about the sexiness of cava as compared to red wine. Neither of us know a thing about wine, but decided to settle it once and for all. We will be meeting and tasting the two, as well as some others (if we can). The problem is, I have no idea what is good wine, what is bad wine, and how much it should all cost. I'm particularly interested in the cava, since that was my side of the argument. Does anyone know what I should buy if I'm looking for 4 bottles total? I'm thinking one cava, one red wine, one champagne, and one white wine (we're going to gather some friends). I can spend anywhere from $50 to $125.

Suggestions?