I don't own a Nikon but I think the Tamron 18-400mm is a good lens for the price. I only own native Canon glass but I'm considering this Tamron lens based on what I've read and seen on YouTube so far. Weight seems to be an issue for your for travel/hiking. The 18-400mm weighs 1.56 lbs, a few ounces and a couple hundreds more than the 16-300mm. Good luck with your search and happy shooting.

I ordered from B&H the other day. B&H sent them on two separate packages. Package 1, containing a flash stand, no signature required from UPS. Package 2, camera flash, compact flash card and reader, and lens replacement foot, signature required from UPS. I like signing for my items but B&H made an error this time. I paid for a 2-day delivery but Package 2 (signature required) is being delivered on the 3rd day when I'm not home. Ouch!

I use the Canon 200mm f2.0 IS and a 400mm f2.8 IS (older version) mainly for sports (including surfing) and birding. Depending on subject distance I use a 2x extender, with slight image quality degradation (softer). I also use the 200mm for portraits, producing outstanding bokeh.