I will be taking pics of my kids and my aquariums/pets mostly, but I will also want something for landscapes etc.
The Nikon 18-55mm kit lens is a cheap plastic mount. I would personally skip it unless thats all my budget allows.
I suggest the Tamron 17-50mm f2.8 (Non-VC). Its about $300 brand new though. It can come in a Nikon F-mount so theres no need for adapters. You can do landscape and mid-zoom shots with a constant aperture.
Primes are nice and sharp but it might not be versatile enough for the uses described. Youll find yourself running back and forth just to get the subjects in frame. If you dont midn that then the Nikkor 35mm or 50mm f1.8 is a winner.