Doing mainly portraits on Nikon FX cameras, these are the ones I like:
The 85/1.8G. Don't leave home without it. It's an amazing lens at a bargain price. DO skip the D lenses.
The 105/2.5 AIs. The classic Xenotar design has superb bokeh, and when stopped down to f/4, gets excellent sharpness and contrast. It feels good to use this lens.
The 135/2 DC. This is my favorite portrait lens of all. Don't be put off by the listed focal length. At close focus this is a 115mm lens. The bokeh is as good as bokeh ever gets. This lens has a magical look. From f/3.2 on, it's razor sharp from corner to corner. And that's a good f-stop for portraits on this lens, giving you a nice smooth transition from face back.
The 180/2.8D ED-IF. This is my top lens for big face portraits. This is about 150mm at close focus. The bokeh is wonderful. It's a nice sharp lens, even wide open. Working distance is comfortable for the subject. The lens is compact, and balances perfectly on the D3s.
The 75-150/3.5 E. This cult classic is truly an amazing piece of glass. Really looks good in portraits. Really good. Costing around $125, you can't beat this lens for feel with anything, even a 70-200/2.8g VR-II.
Next on my list:
105/2 DC. Obviously.
60/2.8g micro. So clean, with near zero distortion. A great lens for fashion portraits.