To the OP's question, if its macro you want, then save up and get the 100mm f/2.8 Macro or the EF-S 60mm f/2.8 Macro. (Or the Sigma or Tamron macros near 100mm.) There is really no substitute for a true macro lens.
The 100mm-ish macros are relatively large for a 100mm prime, but I really love mine.
The 50mm f/1.8 is a good lens for beginning street photography (with an 80mm-equivalent focal length). It is definitely the least expensive way to add new creative possibilities to your photography kit.
However, for tourist stuff, I still find that the kit lens stays on the camera more than the nifty 50.
The Canon EF-S 55-250 IS is also a good inexpensive upgrade for your Tamron 55-200.
|AF4_2483 Surfing the Serengeti by DaveInHouston|
from Hot Air Balloon view
|Peregrine Falcon by Psychic1|
from Best Wildlife Photo of the Week - 4