The city should be wonderful at this time in spring! Take the harbour tour and see all the interesting buildings and much of the city.
I went the end of October after 9/11 so there really were not that many tourists around. I stayed downtown at the Sheraton Towers .. and it was a very pleasant hotel. Good location and LOTS of places to shop and eat within walking distance.
Um .. on the seamier (steamier) side .. all I can suggest is a very intesting book store that was walking distance from the hotel. Sorry no name ... but perhaps a search. Was a most friendly place
I'd love to go back as I really enjoyed the city .. but American Airlines no longer serves it nonstop so it is a bit more difficult to get to. When I have to go thru London and make a connection .. that connection is usually to my other favorite city - Amsterdam!