For landscape your current 18-55 kit lens is good enough, get a polarising filter for it and you will see a big improvement. For photos at family functions etc I would get the Nikon AF-S 35mm f/1.8G DX I would be aiming to snipe one for around the £100 mark in excellent condition on eBay. You will be able to take amazing pictures indoors at functions without a flash and your pictures will look so natural and warm. You will get a nice bokeh (blurry background) which makes your subject really stand out, I like lights in the background that can work well. You will be able to sell it on with little or no loss when you are done with it. The kit lens goes down to 18mm which is pretty wide angle for landscape. Nikon do a 10-20mm DX zoom landscape/wide angle but it costs £300. If I wanted wider I would just use a phone with a very good camera (Samsung S8 £150+ for a 2nd hand one with a cracked screen). Just my opinion... :) I once wanted to get the Nikon 14mm prime (£1400) to do wide angle but came to my senses as I wouldn’t have used it enough to get the value so I went with the 24-70 2.8 (£1100) and it has been to Australia, America, Spain, Greece etc and taken great family pictures and I haven’t regretted it. However I am now thinking of selling the 24-70 zoom and just getting a range of 1.8 fx primes because they offer the best performance/value ratio for a hobbyist and since I have kept my D7000 body (I have D610) I can carry 2 cameras with a 1.8 prime on each and get better pictures than if just carrying a zoom on 1 camera.
Oneday77: What does it not do that you want it to? If you want better image quality but a similar range to what you have. Look for a 17-55mm f2.8. The DX pro lens. I'm still relatively new to photography, only had my D5100 for 2years. I've only got the basic 18-55mm lens. At the moment, I've been just capturing photos at family functions, and the occasional day out somewhere like Alton Towers. I would like a better lens to help take photos in low light at family functions, and an additional lens for landscape photography, for when I go to the countryside like at farms and theme parks etc.
It depends on what type of photography you are interested in. 18-55 is a basic kit lens but good enough for general everyday family pics. If you like the 18-55mm lens but want to upgrade from kit lens inn the same range. I have Sigma 17-50mm 2.8 lens and pic quality is absolutely wonderful. Having 2.8 aperture will give you smoothly blured back ground "Bokeh" and enable low light photography. I also have Nikon 35mm 1.8 lens and it is a fantastic light weight lens. Very fast and 1.8 aperture is brilliant. As you have Crop sensor DSLR 35mm is equivalent of 50mm that every one talk about it on YouTube.
What does it not do that you want it to? If you want better image quality but a similar range to what you have. Look for a 17-55mm f2.8. The DX pro lens.
The 85mm f1.8 G is the muts nuts.