compact double v triple? (my new bike!)

[RussianHillGal]

After an all-day bike shopping trip with a very patient girlfriend/TNT cycling coach and 3 weeks of peppering my cycling friend with questions and spending countless hours online, I was convinced I had caviar tastes on a filet mignon budget, so I decided to take a break from active bike shopping and tagged along today on another gal's bikeshopping expedition to a boutique LBS. I was just there to watch/look/listen, and of course, as we were getting ready to walk out the door, the sale tag on a pink and silver flash caught my eye. Three minutes later, I was in love!!!

Giant TCRw 2006, Shimano 105, aluminum with carbon fork. About $300 more than the Dolce I looked at last week, but this bike has better components - and it is SEXY!

There is a reason this LBS (Bike Nuts in the Marina district of SF) is so highly recommended - the service is impeccable! This place doesn't advertise, and the only pressure to buy came from my girfriends who could tell I was in LOVE!

The TCRw comes with a compact double. The LBS guys said they could swap it out for a triple and install it for almost an even swap. So the decision really comes down to preference, not price.

I am 33, haven't been on a bike in 20 years (yeesh!), and would say I am average fit (just finished a 25k xc ski marathon with Team in Training, as a total beginner Dec 06 - but I am slooooow - and not terribly coordinated). Short legs. 5'1. Have probably 15 pounds that need converting from fat to muscle.

Plan on riding with my cycling girlfriends in the crazy hills of Marin County - Sausalito/Tiberon/Larkspur - the goal is to train for the Marin Century. Apparently 30-50 miles/day is the norm with "the girls", so that will be my training target.

Would appreciate your thoughts on whether to keep the compact double or swap it out for the triple. If triple, are there any things I should keep in mind so I can discuss this intelligently with the LBS guys?

I'm going back next Saturday for my first hour-long fitting (I get another fitting for FREE with these guys after I've spent some time on the bike and my fitness level has improved - how's that for awesome service?) Am so excited!!