tjspeil (#2) -- It's ridden to work. That's really what it comes down to. --- Amen, brother ;o)
I live in a hilly area, no long or very steep climbs but many small ones; my six mile fitness lap climbs a total 1300 feet yet no one climb is more than about 300 feet. There is no place I go where I do not have to climb a hill, however short it may be.
I am 74 yrs old, 6'1" with a BMI of 29. I am not fit and am 40# overweight. My everyday bike (the one I ride every day) is a full-suspension mountain bike with 3x9 sprockets and 16-104" overall gearing. It is right for me and where I ride.
The suspension and Schwalbe 50x559 "Kojak" slick tires give an incredibly smooth and high-traction ride, and, I don't have to dodge little cracks, small potholes and drain grates. Also, this bike can easily carry a rather large person (see: Clydesdales/Athenas in this forum) without collapsing wheels, etc. Mountain bikes usually have wide and relatively low gearing. They are very strong.
If I lived and commuted in a flat area, I might use my half-step + Granny 2013 Cannodale Synapse or maybe even set my 1989 Merckx as a fixie/single speed.
My Advice: Set your bike up to fit your personal needs and capabilities together with where you ride. Ignore the TDF wannabies.
Joe