Carpe diem - Sieze the day.
Carpe bicycle - Get off your butt and ride!

Seriously, both Trek and Giant build quality bikes. Go with what feels best. However, don't get hung up on the saddle. Any LBS should be willing to make a swap to another model saddle for a small charge. The important thing is the bike fit you. The shop you buy from should spend some time making sure the bike is the right size and set up correctly for you. Other than that, what are you waiting for?