If you are thinking of going to DM, here is food for thought.... Most shops (probably not all though) really advocate owning the same manufacturers gear that they sell. Now you could go with whatever is in your budget, personal preference, etc, but once you sign on to a shop, you may find yourself needing some new equipment. You may get some good deals through the shop once you are a DM for them, but it is something to consider at least.
The shop I work for sells Mares, Tusa, AquaLung/Apeks, Sherwood. I started with a Sherwood Maximus (under-arm hose setup) which was great for being low profile for me. I recently got a new reg though - Apeks XTX200 and am migrating the Maximus to my Pony Bottle setup. I bought my wife an AquaLung Legend ACD.
Monterey is not too cold - I would say just on the border of cold. I have dove there a number of times and am actually from the Bay Area. The AquaLung Legend series has a cold water and non-cold water set up, but honestly, the ONLY difference is like a 1/4 turn on the inside of the reg. That and the cold water has a silver ring, the non-cold water a gold ring on the outside. That geing said, once you know which directio to turn it, etc, and as you get more diving & diving equipment experience, it would be a VERY minor task to re-set the reg as needed for Monterey vs warmer water diving.
The regs that get the most acclaim in magazines are Atomic, AquaLung/Apeks and ScubaPro. There are many other manufacturers out there, but some of them are just smaller shops that don't get the smae acclaim, but are no lower in quality - eg Sherwood, Oceanic, Tusa, Mares.
Your best bet is going to be trying out a few of the brands at shops in your area - write down the model names and then research the heck out of them.
I do love my Apeks and AL though.
Hope this helps...