If you after 35mm - have you considered the Zeiss ZK 35/2. It is a stunning lens, meters on the K5. The disadvantage of the Zeiss 35 is - it is manual focus.
I use mine mainly for
landscapes, although there is one
portrait.
I had a Pentax 35/2.8 Limited Macro which I really liked, but I sold it as I was never using it - I would always reach for the Zeiss every time I wanted 35mm.
I have also used a friends Pentax FA31 and that is also a very good lens. If AF was important to me I think I would take the FA31.