For the Pentax, a Vivitar / Kobori 35-105mm f/3.2-4. I really liked the 28-105 with serial #77---- and this is from that same firm. This one is a bit faster, misses out on the wide end but takes 55mm filters not 72mm. I own several 55s so that's a bonus.
That was all I planned to get .. until a Samsung 20/2.8 appeared for $100 less than its typical lowest price! Similar to the 30/2 that I like a lot, but slightly slower and a bit thicker. Still quite small for a 20 plus it has the i-function on the lens, which can be handy for quick changes to settings.
With this in hand soon, I can sell the 20-50mm; never thought that tiny zoom would be one of the larger lenses in my kit! Its only real issue is its inability to easily use a polarizing filter as focus will rotate with the filter dial.