Intrepid Bicycle Commuter
Joined: Sep 2009
Posts: 819
Likes: 95
From: Upstate New York
Bikes: 1976 Motobecane Grand Jubile, Austro Daimler 'Ultima', 2012 Salsa Vaya, 2009 Trek 4300, Fyxation Eastside, State Matte Black 6, '97 Trek 930 SHX, '93 Specialized Rockhopper, 1990 Trek 950
I wouldn't want to do your commute on a Trek FX. 20 miles per day is too long for a flat bar bike. I'd be more inclined to stick with the Lexa, and use a good quality backpack or messenger bag instead of a rack.
If you need to stick with Trek, and want to swap, see if you can get your hands on maybe a Trek Lane, if they make one in your size. It's more of a drop bar road bike, but designed to handle commuter type needs. Don't get too hung up on women's specific bikes. A lot of that is just marketing. Buy a bike that feels good to your body.
You can comfortably do centuries on a flat bar bike, but that bike has to fit you VERY WELL. I'm talking that level of fit where you swear that the bike was made especially for you. It's a lot of work and luck to get a bike to fit that well.