Need help choosing a new zoom lens

[DelawareJim]

I'm looking at getting a new zoom for Christmas and I'm torn between the Nikkor 55-300mm f/4.5-5.6G ED VR AF-S DX or the Nikkor 18-200mm f/3.5-5.6G AF-S ED VR II. They also make a 28-300mm f/3.5-5.6G ED VR AF-S, but I had sticker shock when I saw the price.

I currently have a Nikon D80 body, an 18-55mm and a 55-200mm and find I'm switching lenses a lot and want a little bit further range as well. It'll be used almost exclusively for field work shooting plants, wildlife, and such.

For those who use zooms a lot which do you think would be most practical.

Thanks.
Cheers.
Jim