I've used internally geared hubs for my commuters for about 5-6 years now, and love them. Something to consider for sure. Any old frame with horizontal dropouts can be used, and you can buy a pre-built wheel with a Nexus 8-speed (28 gear inches to about 90 gear inches with typical setup).
The chain line is dead simple, clean, and the maintenance is almost nil. I love 'em.
If your terrain is flat to modestly hilly, a sturmey archer 3-speed is pretty bombproof.

Well, different folks have different needs. I admit I like bicycles of a certain quality. However, if I had to leave a bike outside in a dodgy environment, I'd definitely go with something that looks old and worn (even if it is built well).

I misread your post - with your mention of a nicer steel frame with 105/ultegra grade components, it implied that you were looking for something decent. Frankly, a bike with ultegra is hardly a beater