I'm just getting back into it, post CanJam, and now have the following setup:
40D body
24-105mm f/4.0L IS USM
50L f/1.2L USM
70-200mm f/2.8L IS USM
My first priority now is to get the ultra wide angle range covered. I'm planning to spend more and more time in the Western states as well as Alaska in years to come and really enjoy landscape photography. Having wide angle capabilities for low light indoor events is also a big draw. Here are the two I'm considering:
14mm f/2.8L II USM
16-35mm f2.8L II USM
The 14mm lens seems to be more highly regarded in terms of sharpness, and it gives an even wider FOV, but of course it also costs $700 more:
Canon | EF 14mm f/2.8L II USM Autofocus Lens | 2045B002 | B&H
Canon | EF 16-35mm f/2.8L II USM Autofocus Lens | 1910B002 | B&H
The only drawback to the 14mm lens is that you can't put any filters on the blasted thing! Thus, I'd probably mess it up in no time. That has me quite concerned, so I'm kind of leaning toward the 16-35 zoom. Besides, I like to play with zoom lenses. Somehow that makes me feel like I know what I'm doing, whereas in reality the zoom feature very rarely makes any difference at all. You can always crop later.
My second priority will be to (one day, but maybe not soon) pick up a 1D body, either a 1D Mark III (for about $4k) or a 1Ds Mark III (for about $8k). Here, the price difference becomes much more relevant, and although I've read quite a bit about each body, I'm not sure I understand it all.
What I do understand is that the 10 fps burst rate on the 1D Mark III is a blast to play around with. One of the guys whom I was hanging out with a a track event last week let me shoot for a while with his 1D Mark III using the same telephoto lens I use (70-200 f/2.8L). As luck would have it, he put his Atom in a spin and I caught it all with just one burst.
Obviously, there are a lot of advantages to the 1Ds Mark III but I don't see the 21.1 megapixel thing as any big deal. I suppose that would matter a lot more for professionals who want to blow up their shots. I'm just wanting to grow into the hobby a little more and don't really have highly particularized needs (i.e., I don't see a whole lot of sense in buying a 1D or other FF body at THIS precise point in time, but know that I will one day... just because).
If the 1D Mark III was FF instead of a 1.3 crop, that would probably seal it for me. But even a 1.3 is a nice move in the right direction. Or maybe in another year or two a used 1Ds Mark III will cost considerably less than it does today.
My third priority would be (depending on if I go FF or 1.3) to get a couple more prime lenses to augment or possibly replace my 50mm f/1.2L. Here, I'm thinking of the 35mm f/1.4L USM, 85mm f/1.2L II USM and/or the 135mm f/2.0L USM. This is a distant priority and something I won't know until I've grown into hobby considerably more than I have at this time and can break down some situational needs (indoors, low light, portrait, sporting events, etc).
For now, I'm just trying to figure out what zoom lens to go with before I end up someplace like the Grand Canyon without one, and then start getting grumpy about the lost opportunity.
I'll keep the 40D in any event, as a 2nd body. It would be especially useful for long throw telephoto shots (Grand Canyon again). Using a 1.6 crop and a 1.4 or 2.0 extender gets you pretty far with the long end of a 70-200mm lens. It might not give you the same results as a 1D body and a 600mm or 800mm lens, but it would cost a lot less money and produce pretty decent results for just clowning around. That, and carrying those massive lenses around must be a real pain.