Personally, I think the best part of urban geocaching is to take the searcher to areas of intrest in a particular city. Included in the cache page should be some commentary regarding exactly what is so interesting about the area. Perhaps even a bit of research might be required that teaches searches something about the areas history for example.
Altoids tins with attached magnets with a plastic bag protected log works well. It also adds to the fun if a high level of stealth is required.
I once located a cache in Detroit that was well disguised as a sprinkler head outide of a well known building. Because it was in a high traffic area, I visited several times without being able to actually retreive and log the cache. Because I work as an electrician, I eventually donned a tool belt and hard hat and approached the cache with tools in hand as if I were working on the sprinklers. None of the passing muggles were any the wiser as I hid signing the logbook by feigning a spinkler repair.
