Join Date: Jan 2005
Location: Directly above the center of the earth
Bikes: Varies by day
Welcome back to cycling! Unfortunately, I'm not familiar with the Trek line, so I can't advise you on that. My choice in "upright" riding was an Electra Townie. After the first six months, I discovered I couldn't ride for more than an hour at a time without being SORE. The "upright only" riding position combined with the "cowhorn" bars gave me a sore keester and tennis elbow.
I sold my Townie and bought a bike that I converted to a "English racer" style with the down-turned handlebars. Surprisingly, I find this bike more comfortable (after a week or two of adjustment on my part), because of the multiple seat/hand positions available.
If you're sold on a "comfort bike" and are sure it will work for you, then go for it! Otherwise, consider other styles before you buy. It may cost you a little time, but can save you a lot of money! The difference in stress on your knees is zero.
Happy shopping & riding!