First welcome to the Pentax Forum.
Originally posted by Eliglass 1. Good walk around zoom for when it is not convenient to change lenses and I need reasonable reach.
DA18-250mm
For me a walk-around (or all around lens) is one that stays all the time on the camera. My recommendation is the Pentax DA18-250mm.
Like the Sigma, the DA18-250mm does not have quickshift. It is lighter than the Sigma, and has an outstanding record as a very solid lens. Manufactured by Tamron (and sold also as Tamron 18-250mm), there are a number of good quality used ones on the market (keh, adorama, PF marketplace) between 350-450 US$.
The lens IQ is well regarded among the all-around lenses across all brands.
Originally posted by Eliglass 2. A sharp prime lense for portraits and general photography..
Pentax FA31mm f1.8 Ltd. This prime is legendary and great, great lens. The focal length is an excellent compromise between wide and close-up. The lens is fast. This is the most polyvalent and useful prime that I have, and it is highly regarded by all Pentaxians.
Hope that the above comments will help.