Well now you need to figure out what you are going to focus on.
If you just want a lens to compliment your 18-55 then fill the gap with the 55-200, 70-300 or anything else in between. Night time shots look to spend more on lenses that offer a wider aperture F1.4, F1.8, F2, F2.8 primes and more expensive teles will fill these gaps.
Everything around you is experimental, from people, nature, wildlife, plant life, concrete to the cracks that break it. You need to know what you want to focus your photography on, as there are no set lenses that will fully fill a gap on everything. Every lens does certain things better than each other. Primes, Macro, Telephoto... You can say you want to do this and that, however you can easily find limiting factors in this hobby. Pricing and your budget will come into play.
If you can go and purchase something used, maybe this will help you with getting another lens, but do research as you can easily find out that you may end up not liking a great lens, because you find no use for the lens.