Hal,
Look, I will be the first to say that the agencies are too happy selling certs, but, if you are trying to get used to doubles, a wing, dual regs, etc, the last thing I would recommend is topping it off with a new drysuit. Not that I am saying to go running to PADI or any of the others for the drysuit class, but, get used to one thing then the other. Doubles are awesome, and so are drysuits. I had over 100 dives dry before I got around to getting a card. And as far as I know, there is no doubles class- though I am sure some agency will come up with a intro to tech that really is an intro to common sense.....The other thing- find a shop that will do the dry course in a shallow part of a lake or quarry. NEVER! NEVER! NEVER! put any gear you like into a chlorine infested pool- it will destroy it- end of discussion. If they insist on the pool, have them hose you in the drysuit before entry, as this will alieviate absorbtion of chlorine.
Just my 2 PSI
-J