For the kind of hard use you are likely to put on this, I would pass on anything with a 7-speed freewheel hub. A cassette type hub with 8 speeds or more is inherently stronger since there is less unsupported axle length. I think that 8-speed in particular is an excellent pricepoint for the operational costs of a bike over it's lifetime. This is exactly the upgrade I made to my 1977 touring bike when I moved to Europe.

Since your taste in riding position will likely change a bit over time, something with a threaded-style stem, so you can adjust it up/down as needed over the first year of ownership, may be a good choice.