Join Date: May 2014
Location: Fairfax, VA USA
Bikes: Trek 7.3 fx, Domane 4.7
Welcome from another newbie! I too just got back into riding, and bought a flat bar Trek 7.3 fx just for the exercise. It's a great bike, but as I quickly got into shape, I kinda out grew the posture this type bike has me in. It's just not that much fun after 20 miles to continue in that same position. I plan to do longer rides, and this bike won't be a good fit for them. I picked up a drop bar endurance bike (Trek Domane 4.7), and coulda saved if I had listened to the bike shop guy who knew better than me.
If you are going to go out for light action, 10-15 mile rides then the flat bar is a good bike - especially if you also want to try commuting (putting bags and racks on this type would be a tad easier, at least between mine, and how I will be purposing the 7.3 from now on). If you want to do longer distances or think you will be riding with others that might have endurance type bikes with drop bars, look at that as your best option.
The drop bars give you several options to reposition yourself where the flat bar offers but one really. That's a big thing on longer rides. You will appreciate a strong upper body and core muscle groups with either style bike, or prepare for some numbness in your hands (you'll be resting too much weight on them holding up your body). When you have a strong core, the lean you have with the drop bar isn't going to hurt, and maintaining that position is positive for strength in itself - win/win!