Hi!
When selecting the lens bear in mind that the field-of-view (FOV) on your 28-80 mm lens will correspond to FOV of a 43-122mm lens on a film body.
Therefore, if you like to do landscape photos, you will need something wider. The best value for money would be the kit lens (decent build quality, optically very good if you consider the price). The FOV of the kit is equivalent to 28-84mm on a film body. On this thread
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/14547-kit-lens...tml#post116119
you will find some samples what can be done with the kit lens
The 1.4/50 mm (fov as approx. 77mm on a film body) is an excellent lens but is more specialized (low light, portrait, .....) .
On my PBase site (switch to "original"size, and press F11 in your browser) you will also find some samples taken with 1.7/50mm, which is considered still a little bit better than the 1.4/50. You can compare them to the other pics.
I hope to have been of help.