Hi,
I can only tell you about Mexico, Baja Mexico to be exact. I see them fairly often at different times of the year on some of the Seamounts I dive, but you can find them more often up in the Bay of Los Angeles area, and also just outside of the Magote in laPaz Baja California Sur. I generally find that the Vis is better in my area, but you cannot depend on them always being there. I would say the B of LA would be a sure thing in the Summer months....and they are big, with some reaching 35 to 40 feet in length....remember, touch is cool, just don´t grab the tail, or you could end up getting a nice size slap that could ring your bell...hee hee. I think they feel much the same way you would if someone grabbed both of your fins.
Have fun and stay safe, Terry Kennedy