I know of some raifanning spots...
Hobby shops in the main City area: none that I know of
Railfanning spots: Some of the best (if you have the time)
First and foremost: CINCINNATI UNION TERMINAL. The still in use rail station was the last of it's kind, built to replace five smaller stations. After rail service origionaly stoped and the place was abandoned, some contractor attempted to turn it into a mall. He ended up only ransacking the place. In the end, some historical society (froget the name) and the city bought the entire complex for $1,000,001. The one million was for the land, the $1 for the actual building and everything in it!

Today it's the museum center, but traces of it's glorious rail history are still there. The REALLY big mural is still there, all the offices, board meeting rooms, etc. have been restored, and Amtrak has a daily train stop there! Plus, tower "A", the origional control tower (still have to go there myself!) is there and has been restored to the limit. There is now a rail yard behind it, which should make for great railfanning, along with some other smaller, scattered about rail yards. You might get lucky, and see a promotional end passenger car by a Montgomery Inn restrurant on Columbia Parkway. Lastly, be sure to take one of the special tours that take you into the inner dephs of the place, you'll be amazed!
*pant* ok, now the Cincinnati resident will return to his seat:mrgreen: