Responding to various posts, so won't quote... You know who you are
Cabo Pulmo can get as deep as 70 ft if you work really hard at it. CSL near Neptune's Finger/Pelican Rock can get as deep as 3000 ft if you don't pay attention (just follow that grouper a little further down
) The DM's won't take you to Land's End (just on the other side of the sea lions) until they're sure of your skills, as the surge can get interesting.
I think dlndavid did do Gordo Banks on a Cabo trip report. He loved it.
The scenery & landscape on the drive to Cabo Pulmo, on the East Cape, in my opinion, is worth the drive. And the beach/sand/etc. is finer than the usual Cabo sand. If I had $$$$, I'd own a house on the East Cape.
For Sushi, as of May/June 2005, Solomon's Landing had a new sushi bar w/ sushi chef. He beats everybody else hands down.
For Huachinango Entero (whole fried snapper with garlic salsa on the side), the "Fish House" (upstairs at the ballerina sculpture, can't miss it) does the best one. Their side of garlic sauce (Mojo de Ajo, I think) is out of this world. (But also a touch spicy). I wouldn't bother with any 'lobsters' anywhere in Baja.
There's a Chinese restaurant in Plaza Bonita mall upstairs. Avoid it like the plague, even if the waitress is cute and blonde. (Or, if I may, avoid it as if the cute blonde waitress had the plague!) It was *SO* bad that I've scrubbed its name from my memory.
The Sea Queen restaurant at the corner of Ave Cabo San Lucas & Marina Blvd has an attached coffeehouse. By all means, stop by the coffeehouse and have some coffee and pastries. The pastry chef there makes the best pastries that my wife has ever remembered (she lived for 13+ years in Paris, and my mother-in-law has taken Cordon Bleu classes, for your reference). We especially love his chocolate cake (mmmm) and his apple tarte (yummmm).
I personally don't think that you can go too wrong with any of the dive ops in town, but then, I'm pretty easygoing. I've used Baja Dive & Land's End personally; and I've heard good things about Deep Blue. If someone is at the Finisterra, Amigos Del Mar's shop is the closest to Finisterra; just walk down the road from Finisterra towards the marina. Amigos Del Mar is right there near the new Dolphin stadium on Marina Blvd.
Most of the dive ops are in the building which was formerly the Plaza Las Glorias.
There are at least two ops on Medano Beach (Cabo Acuadeportes & Manta). Manta is near the Mango Deck restaurant on Medano Beach; Cabo Acuadeportes is near the Hacienda hotel.
Water temps in April will be cool. The locals will all be wearing 7mm. You might get by in a 5mm.
For non-diving things, it depends on what you like to do. If you're into outdoorsy activities, lots of stuff going on (golf, parasail, kayak, etc.) If you're more into sightseeing, I think Todos Santos is worth an excursion, as is San Jose. My wife & oldest daughter love the guided horseback rides. I think they may do a Corrida (bullfight) weekly at the edge of town in Cabo, but the Mexican bullfights are different that the Spanish ones. No bulls are killed in Mexican bullfights.
Have a great trip!