I presume you are talking about using digital ...
If 28mm, still OK for walk ard, but I feel the lense may not be wide enuf.
the 70-210 is a good lense but then again, the range may be too long for street/general shooting.
y don't you consider getting a 18-70 and a 70-210 ? I feel this two lenses combined has a more usable range. Either that or, if you don't mind spending a little more, get the 18-200 VR, a good and light travel lense. saves u the hassle of changing lenses too.
Just my 2 cents ...