Once you start getting into wide angles, then you have to think about auxiliary viewfinders, and the amount of things rolling around in the bag starts to grow. Also, remember that you should budget for a light meter, if you don't already have one.
A lot of people simply guess, but if you're going to ever shoot slide film, then you'll need a meter. And if your sole experience has been with digital, you'll definitely need a light meter. I recall that one person said that their exposure estimations were more accurate than a light meter, which is preposterous.
I would suggest getting a IIIf and a Summitar or Summarit and then shoot with that for a while. Changing lenses on a Leica takes a bit of time, because they screw onto the body. Also remember that loading film takes longer than other 35mm cameras.
Good luck. A Leica is a great classic camera. The screw-mount models are svelte, unobtrusive and great shooters.