1) Canon 28-300 F/3.5-5.6 L IS

2) Canon 24-70 F/2.8 L plus Canon 70-200 F/2.8 L IS with extender

Neither of these options is remotely cheap, so I really want to make
sure I get this right first time! I also don't want to be buying lenses
again in 3 years or so when the 10D is old hat and I'm looking at a 16mp
digital slr for $1500

On the one hand, I like the idea of a single lens, as I don't like
changing lenses all the time (dust, extra weight, possibility of
dropping one). This puts the 28-300 in a good light. But, it's a darn
heavy lens to lug around *all* the time (for example, I'm doing candid
shots at a wedding in December). And 3.5-5.6 isn't a particularly
spectacular aperture in the scheme of things, although the IS gives you
a couple of extra stops.

On the other hand, the second option appeals because of the large
aperture throughout the range - it'd give me 24-200 at F/2.8 and 140-400
at F/5.6 with a 2x extender. But then I'd have to change lenses when I
wanted to move up and down the range. And would I always have the right
lens with me? I also like the fact that both these lenses are rated
very highly for optical quality by people who use them, and the 70-200
seems less prone to dust because of the rotational zoom action. The
24-70 would also give me a little extra space at the wide angle, but at
the same time, it doesn't have the IS which I find so appealing.
Finally, with things like weddings, I wouldn't have to lug the bulk of
the longer lens around unless I thought I was going to need it.

Does anybody have any comments on this decision, based on previous
experience with any or all of the above kit?

There is an option 3) Canon 24-70 L plus Canon 70-300 F/4.5-5.6 DO IS,
more limited but a lot cheaper, if anybody has comments on the 70-300
lens.

I have the lenses in option 3 and to me this is the best combination. The
70-200 f2,8 L IS (I have the non IS version) is a bear to lug around and I
find it a bit short even with the crop factor. I also find that the f2,8 is
somewhat wasted because the depth of field is so shallow when wide open and
at close range. Since the 10D is so good at 400, 800 and even 1600, a lens
does not have to be that fast so you end up paying too much for what you may
not use that often.

The 70-300 DO IS is a very nice lens, not so long, not so heavy and the
focussing is fast (not as fast as the 70-200, but much faster than the
75-300).

I have just bought a Kenko 2X teleconverter, the jury is still out on that
purchase. So far it does not allow focussing on my 70-300 because there is
too much light loss. Using it on the 24-70 is a waste, I would rather
switch lenses. I have made some test shots on the 70-300 in manual
focussing mode and at 300 x 2 with the IS turned on, it seems to work rather
well. If you really want a teleconverter, don't get anything over 1.4X.

I am not a wide angle nut so I can live with 24mm on the wide end most of
the time, If I need wider, I still have the 18-55 from my Drebel which I
modified to fit on my 10D.

Jean