[eeyore]

personally for wildlife i'd be inclined to look at getting some longer glass rather than shorter (something like the 100-400 f5.6 or the sigma 50-500) as with the two times converter your f4 lens becomes an f8 which will create autofocus problems for all but the most expensive cameras.

at the very least i'd get a matched 1.4 tc to give you equivalent of a 420mm f5.6.

also for street and candid photography you could do with a wide angle lens such as the sigma 10-20 or the 12-24.

theres no doubt that the 70-200 f2.8 is a nice lens but it wouldnt be my first choice in your shoes