Originally posted by TheWengler I would drop more money on the zoom since I would use it more but if you think you'd use a prime more then emphasize that. The wider the better for landscapes as well. You should also give some consideration to the Sigma 18-50mm f/2.8 to compete with the Pentax 16-45mm f/4.
I'd prefer to use primes if I can, but finding something in the realms of 16 - 18mm end is quite a bit expensive, and seeing as I might only use the wide angle side on interior shots, I wouldn't as likely use it as much as I would a 35mm-50mm ish prime.