I only commute 1-mile each way, so I'm probably not the best person to ask. But I just bought the 06 FCR3 for my birthday earlier this month and am just loving it. It's less than half the weight of the 13yo cheapo Huffy mountain bike I was riding to work. I like the 28C tires it came with (I think the 07s will have 26C tires on them) for giving me a good compromise on speed and comfort. I'm able to start and end in the 2/6 gearing for the whole trip, where before I would poop out going up a hill on the old bike unless I shifted a few times to make it easier. I'm not 40 yet, but I sure don't bike like I did when I was a teenager.
I also don't mind the flatbar. I'm not on the bike long enough to hate it, but it does give me a nice upright ride. I tried some of the true road bikes that my co-workers have (they bike longer distances) and those skinnier tires were not for me.
I think the FCR is designed for up to 30-mile trips, which more than satisfies your range.
Either way, I don't think you'll go wrong with either bike - go try them both out at a Giant dealer. My friend is the state's Giant rep, and he thought the Sedona was the one for me based on what I told him. Nice bike, but I hopped on an FCR just for grins and giggles and thought it had way more 'pick-up and go' and my mind was pretty much made up! Now I can go on lunch rides with the co-workers and have a decent chance of keeping up.