I'm not sure the extra 50mm of the Tamron would be worth giving up VR of your Nikkor. I have the Tamron 18-200mm and it's a great lens for the price I paid ($150 slightly used), but VR is one of the saving graces of long slow lenses in this category. The Tamron 28-300mm VC is one I really have my eye on... my first dSLR lens was an older Tamron 28-300mm and it helped me make the transition from a string of super-zoom p&s cameras. I let it go when I upgraded to Sigma EX f/2.8 zooms, but later picked up another copy for vacationing... it's such a convenient focal length, and VC would make it the ultimate travel lens (I never had problems living without the wide end).