new lenses for portrait/walk around photos/opinions needed

I'm a big fan on the 17-70mm and I own it. I use it as my walkaround lens and love it. The 70mm reach makes a difference to me, as does the 17mm on the short end.

17-70 is sexy and tack sharp. I'd also throw in a 50/1.8 prime in there for good measures.

The Sigma 17-70 and Tamron 17-50 are two highly recommended lenses. The Sigma has more reach but has a variable aperture, and the Tammy has that constant f/2.8 but less focal range. You just have to examine your particular needs to assess which might be better for you.