Don't ignore La Paz. It is my favorite Mexico fishing location. I'll be honest, Marlin fishing from La Paz is no better than from Cabo and to be fully honest, Marlin fishing from both isn't all that (imho) Personally, I think you have to plan on spending at least two days out on the water (spending the night on the boat) to ensure catching a Marlin. Yeah, you can catch them on a day trip, but the odds are stacked against you (again, imho) I like La Paz for it's variety of catchable fish, in the case of Dorado, right from the shore although trolling is more fun. You can expect to catch:
Dorado (aka Mahi Mahi) my personal favorite
Tuna (yellowfin) an exciting fish to catch
Yellowtail Amberjack (easy to hook, hard to land)
Roosterfish (catch & release only)
I quit going to Cabo when it became a party-town (thanks Sammy Hagar) so I tack on the addition two hours drive from the airport and go to La Paz. That's the only downside, the addition drive. You'll save money fishing out of La Paz too