Jackson,
Considering rip18's response, how much are you willing to spend/carry? The Nikon 200-400 f4 is a great lens, but it is big, heavy, and expensive. For many years I owned a Nikon 400 f3.5 which is about the same size and weight as the 200-400 and while I did occasionally use it with extension tubes to photograph lizards it was so heavy that I usually left it at home unless I was working from a car or primarily intended to photograph birds or mammals. The nice thing about lenses like the 300 f4 or 80-400 vr is that they are small and light enough to hike with. Since lizards are most active when the sun is well up in the sky the relatively modest maximum apertures are not a hindrance.
The Nikon 80-200 f2.8 is a great lens that I used with two element diopters for many years instead of a regular macro lens. On it's own it focuses to 5 feet. It is capable of really stellar results, but the af-d version with the tripod collar, (the only one still available new) has a known back focus issue at the long end of the range and even if you focus manually it has a weak spot optically when you combine minimum focusing distance and maximum focal length. Here's a picture from that lens at minimum focus distance and 200 mm.
The lens actually performs better near 200mm with a Pentax T132 diopter attached and the focus set close to infinity than it does on it's own at minimum focus distance, (the actual working distance is roughly equal in both cases). Here's a picture with the lens at 185mm w/ the diopter.
I did occasionally use that lens with the Nikon tc14b teleconverter, which is a manual focus converter that was considered quite good in it's day. From what I've read the current tc14e is even better optically, but it must be modified in order to mount on non af-s lenses like the 80-200 af-d. Here's a picture with the lens and tc14b.
It's a decent combo, but it really does not compare to the 300 f4 af-s. Here's a picture from the 300.
Here's an unsharpened 100% crop of the above image to give you some idea of the sharpness that lens can deliver. If you want to see what it would look like after running it through whatever sharpening routine you usually use feel free to download it and try it out.
Interestingly I occasionally use the 300 with the Pentax T132 and find it is not as sharp with the diopter as the zoom was. I'll probably just buy an extension tube for those times when I need to get even closer than 5 feet. I think extension tubes make more sense on fixed focal length lenses anyway, while diopters are more convenient on zooms.
Finally here is a picture from the old Nikon 75-300 lens at it's minimum focus. That lens has the same focal length range and minimum focus distance as the current 70-300vr, so results should be similar between the two lens, though I would expect the newer lens to be better optically.
P.s., I realize I only provided web resolution pictures of all but the 300mm af-s shot, making a meaningful comparison of sharpness between the different combos impossible. I figured you might be most interested in the frame filling capabilities of the different combos. If you actually want to see 100% crops of any of the others or need to see additional pictures I'd be happy to put them up.
Also, considering Chris's response, you do have or are planning to get a good tripod right? If not I'd make vr an essential requirement for whatever lens you buy. Come to think of it, get the tripod wether you get a vr lens or not!