I would suggest considering a type with higher handle bars to give you less strain on your back and hands. When you are 8 miles in and your back hurts, your hands are numb and your knees are creaking, you'll be wishing you took the time to find a bike that fit you better. The next bike I get is going to be a multi-speed cruiser - like a modern version of a 50's era bike , but my riding is mostly level trails and bike paths.
There's back problems and there's back problems, if you do much riding on a bicycle where the riding position is such that the weight of your upright body is on the saddle, sooner or later you're gonna hit a bump, feel it in your lower back and the next day be introduced to a different sort of back pain called sciatica, which will linger for at least another six weeks providing you don't hit another bump, in which case it will last longer. Ask me how I know, and I ride bikes most every day.
You want your feet below you on the pedals such that they are bearing much of the weight and at least some of the weight on your arms.
Gears are overblown, IMO too. While they aren't much of a cost factor, a 7 speed bike is just as effective as a 21 speed.
A common misunderstanding of the concept. I ride a "27 Speed"; three chainrings up front connected to the pedals, and nine gears in back. I don't ride a "27 speed" I ride an 11 speed. Almost all the time the chain is on the middle chainring up front and the gears I use are the nine on the back sprocket set. If I need a lower gear I shift down to the small chainring up front (AKA the "granny gear"). If I need a higher gear than the regular nine I shift up to the large chainring up front.
So nine gears in back plus one extra-low and one extra-high up front = eleven speeds.
Why nine gears in back is better than seven is that the nine will have closer-spaced gear ratios, more gear ratios available right where you use them most often.
