The info you have given so far makes me think that the current kit lens you own is great for the hobbyist landscape use you are looking for. It has a nice broad focal range from wide to telephoto to suit various types of landscape photograph. The quality may not be as good as more expensive lenses, but the versatility is just right for the traveling landscape use you are after.
If it's a better quality lens you are after then you are starting to move away from hobby photographs and getting more picky about things like chromatic aberration, flare, sharpness etc. I am unsure about the software that comes with Nikon cameras for converting RAW files, but with Canon the DPP software is very very good at removing and correcting things like chromatic aberration which makes even the lower end kit lens essentially 'better quality' than the online review tests show them to be.
If you want to get into Macro photography then another lens would be a good idea, but any prime macro lenses are likely to fall in your current focal range so won't add anything to your landscape repertoire other than possibly quality of the glass.
I would personally recommend getting used to using your current kit lens and cameras manual controls to their fullest so that you can start to get to know any limitations you feel the kit lens might have, which will give you a better idea of what lens you will be wanting next.