Visting Istanbul For the first May 4th to May 8th

Hey Guys i will be visiting Istanbul from May 4th to May 8th, i booked in Mercure hotel Taksim (i heard it is a good spot)... i would like to know what are the good place to visit (not far from Taksim) what kind of bars and clubs to see, places to avoid... should i bring Dollars or Euros? or should i exchange to Turkish money? if there's any singles to join that would be good too.

Thanks a lot