Pentax has a nice line of primes, but I agree with you that it's a travesty that there's a lack of any fast lens with a 24mm FOV. The only alternative is the DA15 Limited, but it might be too slow for your type of photography.
60mm might be odd, but I found the DA40mm pancake useful as an environmental portrait lens. I think the wonderful FA35/2.0 deserves your attention. While it is no longer produced, it can be found used and is a competitive alternative to the more expensive FA31mm Limited. Much smaller and lighter to boot.