Nothing beats going down to the shop and test-riding a few bikes. A hybrid is a great bike to start with. I bought my Trek 720 hybrid 9 years ago and it's the only one I've had. I'm getting a new fancier bike this summer. Take a good long ride, make sure you shift through all the gears and take time to go over terrain similar to what you plan to do everyday.
I like my hybrid because I'm able to commute to work with it, take long rides on the weekends, and do the occassional charity ride. I end up way behind all the fancy road bikes, but that's OK. I can also take it onto some of the dirt paths around here without any trouble.
Is the Sport Double the same as the Tricross Sport Double? That's considered a cyclocross bike which is similar to a hybrid. If you just want a plain old hybrid, you can get one for much less than that one costs. A lot of hybrids have some mixture of mountain bike components and gearing. My 720 does. If you have the money, you may want to upgrade from the Sport to the Tricross Comp. It has nicer components (cranks, brakes, derailleurs, wheels, tires, drivetrain, etc) that will last longer. That's my 'fancier' bike I plan to buy this summer. I really like that Tricross line because it could work for touring and commuting with all of the dropouts and braze-ons you would need to put on rear and front racks and fenders and the long 450cm chainstay length. It's also durable enough to hop curbs and take offroad. It's fast enough because of the road components and weight of the bike to keep up on weekend rides with your roadie friends. Finally, it's comfortable enough to ride for a long time because of the geometry of the frame. If I could afford 3 or 4 bikes, I'd have separate road, mountain, commuting and touring bikes, but this is good enough to serve all of those purposes for someone like me.
In any case, now is a good time to buy if they have your size. Specialized is through making new 2006 models, so stores may be having sales to prepare for the 2007s due out in late June/July. Unfortunately for me, my size is gone so I'm waiting for the '07's. The stores I checked were selling the Tricross Sport for about $1,000 and the Tricross Comp for $1,500. When I tried to order the Comp that they couldn't get in my size, it was on sale for $1,350. For other comparisons of cyclocross bikes, look into the Surly Crosscheck, Jamis Nova, Novara Rivet, Novara Element, and the Trek XO 1. Good luck!