Jaime,
Just to throw something in this as well, but the weather is different from Cabo to Cancun. You get the cool evenings in Cabo b/c it's on the Pacific side, and Cancun typically stays warmer due to the Atlantic. Not a huge deal depending on the time of year, but I was shocked the first time I went to Cabo b/c I had been to Cancun several times prior...it can get chilly!
Also, from DFW, it's a 2.5hour flight to Cabo on AA direct. Continental, Delta, Frontier, Alaska, US Airways all fly to Cabo as well (for your guests).
I've been to both locations before (high school to Cancun, and the rest of my years in Cabo). Feel free to PM if you need help. I find Cancun much more party-style atmosphere, and Cabo much more laid-back, depending on where you are, of course. But Cabo is significantly more expensive (traveling, food, everything) but IMO, totally worth it.
It is beautiful...!