A better and newer alternative for the Tamron 18-270mm id the Nikon 18-300mm f3.5-5.6G. I warmly recommend this lens for overall photography or for traveling, when you need to work fast and cover different fields of view without needing to switch lenses too often. This can be the difference between getting the shot and losing it forever. The best thing is that the quality of this lens is very high, despite the large zoom range it covers.
Nikon 18-300mm f3.5-5.6G ED IF AF-S DX NIKKOR VR Lens