The best roads I've seen modeled used home made decals made using photos of real streets. I've yet to try this but an article in Model Railroader a while ago showed how to do this.
I've just poured an industrial area with plaster (tracks in pavement)...at first I started out real carefully, but when the plaster (plaster-of-paris) started to set up, things changed.
Next batch wasn't so big, but still had issues. Finally I got careless and poured plaster over all the track (my beautiful ME code 70!) and sanded and cleared flangeways after it set (tip:Only wait a few hours, don't wait til the next day, it will be much, much harder.). It was a bit more work to sand (actually I used a hardened metal (machinists 6" scale and scraped it down...less dust and clogged sandpaper), but it looks fine. I tinted the plaster but think I need to seal the surface with another coat of something. I might try to wet the plaster first (so it doesn't suck up all the paint), then paint it with a wash of color...I'm not sure how I'm going to do it (which is why I'm reading these forums) so it's ok for the time being.