Tim,
I sold my 300m m F/2.8 VR at the end of last year. I looked at my LR3 metadata and came up with the following (note: a % of photos taken have been deleted). In 2008, I took 3,548 photos with it out of a total of 10,805. In 2009, I took 0 photos out of 7,109 total. In 2010, I took 148 out of 11,013 total.
2008 was the year that I went photographing Grizzlies. 9,108 photos are left in LR3 from that trip (edited down from about 12,000). 3,452 of those were shot with the 300mm f/2.8. VR. It's a great tool for the right job. In this case, the speed was useful in the varying light conditions. The d___ bears kept moving around!
Personally, I've given up on the big Nikon lenses as being too unwieldy for what i shoot (and want to carry). If, I was going after wildlife again, I'd get the new 200-400mm VR II (with a TC 20E-III) (had both for a while and sold them). I used the old 200-400 VR for 1,050 photos on the grizzly trip. The 200mm f/2 was used for 2,508 photos. The 500mm f/4 VR was only used for 408 photos on that trip. The 200-400mm VR II is big, but, at least it's versatile. Often, the fixed lenses were too much or too little for the shot.
Smaller, lighter , zooms are where I'm ending up: 24-120mm f/4 VR and 28-300 f/3.5-5.6 VR. If you're in a zodiac, you can carry 2 bodies and 3-4 big lenses. I'm usually walking around with one body and lens, so, i want more versatility and less weight.
Sorry, I've rambled on a bit.
Cheers, Matt
http://mdriscoll.zenfolio.com