If it's 2 couples go to La Paz! Great city with cool beaches and great fishing. If you wanna break the 100 lb mark go for marlin or if you're lucky the big tuna will still be at the 88 spot.
I've done a dozen trips since '98 and book through Jonathan Roldan at Tailhunter International. Top notch operation he runs. Not to mention he's got one of the coolest restaurant/bars in all of Baja.
http://www.google.com/url?sa=t&sourc...KZ2sfsqN1moqwA
The expensive obstacle is the flight. Last time I flew Volaris out of Tijuana for $150 round trip. Alaska Airlines Usually runs around $400+. Talk to Jonathan or his wife Jill and they'll help you with that. They know where to get deals if there are any to be had.
I've been all over Baja and I think La Paz is probably the best spot for couples. Took a lady friend 2 years ago and had a blast. Real laid back and friendly town with enough to keep the ladies from getting bored. Great food everywhere you go too. I always stay at La Concha. Great hotel/resort with a private beach, pool, and a couple bars.
Tell Jonathan Charles from Team Modelo sent you. If you make it be sure to take a trip to Tecolote Beach and try the chocolate clams!