Wow, that's a lot of replies! Thank you all guys!
I find it quite hard to summarize your comments ...
Some things one could conclude are
- The Pentax community is really cool and helpful
- There are some primes-only kind of people, but most of you use mainly zooms and a few primes for special purposes
- A high quality medium tele zoom seems to be most attractive (like 50-135 or Sigma 50-150, someday), more than I expected
Seems like this does really make sense for walking around - distant subjects (birds, animals, kids) tend not to wait until you have changed your lens. A wide angle landscape subject can easily wait
- Some of you do own/use an ultra wide angle lens (<14mm), but most seem to use 16mm as their widest.
- Some use relatively affordable tele lenses (e.g. Tamron 70-300), while using very high quality glass in the medium range. Not sure, whether I should go for this lens, though. A crop from a high quality 135mm lens will presumably be almost on par with the resolution of an affordable 300mm lens. What do you think?
- Virtually nobody uses a cheap wide angle or standard zoom (I wouldn't, either)
- I have to make sure to have €€€€ ready to spend before I start