Well I am currently using a panasonic 28 and for last two years have enjoyed taking wildlife pics, mainly in the countryside of Norfolk and Suffolk. I particularly like time spent by the sea with the birds there.
I now want to do more and interested in birds/mammals in the wild but with me walking/hiking rather than in a hide, also birds in flight. I am thinking very strongly of the K5 and the DA* 300mm lens for this - as both are waterproof and reasonably light.
Also I am interested in macro with insects and flowers and was thinking of the DA 35mm F2.8 Ltd (if suitable?) And then the DA 12 - 24mm for capturing landscapes I am in.