I started on a mountain bike with slick tires, after not riding much for years... I had both 5 and 10 speed road bikes that would now be considered classics, but I didn't ride them a lot. First year, I rode 800 miles on that mountain bike. Second year, in Sept., DH took me to buy a road bike. The shop tried to steer me to a flat bar roadie, but I knew better and bought an entry level Cannondale with drop bars. I had it a year and upgraded to a Trek carbon bike. That was 13 years ago and I now have a carbon road bike and a titanium custom road bike that I have a rack on, good for both road riding and casual stuff. I am so glad I didn't get the flat bar road bike that the shop was pushing on me. I had no trouble adjusting to the road bike and I am not that coordinated.
Now, don't get me wrong, there is nothing wrong with a flat bar road bike. I had a Jamis Coda, like Murienn speaks of, for 4 years, as an errand/around town bike. I loved it. I sold it when I bought my custom bike, but eventually, I will get some kind of around town bike like it.