Seconded. Old-school leather saddles are pretty good for riding in street clothes. But, they do tend to require a slightly different fit - I never managed to run one with my normal saddle-bar drop - the Brookes really wanted saddle and bar at the same height and the nose of the saddle pointed up a bit. This was good for ~2 hours or so, never tried it for longer, since I had normal road bike with normal saddle for that.

My old bike had a Brooks saddle and I gave it to someone to use with no real expectation of getting it back, and sure enough I didn't get it back. They're still using it though :-)

I wish I'd swapped out the really nice saddle for a more entry-level one though.