Big Mike said:
Not only that, but you can set the 20D to bracket the white balance setting...but really, that's just a silly feature because anyone that concerned about WB can just shoot in RAW mode and fine tune the WB setting to their heart's content.
I do know about WB on RAW and the like... but you ever tried to shoot at a flower show? (Please, no offence meant.) One or two flowers, it's fine - but when there's a lot of flowers to shoot (and A lot of them are very similar in colour!) RAW simply wouldn't cut it, you can adjust the colour later but there's never any gurantee that what your shot is what you've seen... not to mention the workload of processing them 1 by 1 and whether you have enough capacity in your biological memory card to remember the original colour! Sure, you might be able to make-do with what you come out with... but you just know it's different, yet at the same time you have no idea what the original colour was. I'm shooting for casual purpose BTW, my mom and sis love Orchid and flowers, so it's important to get it right for them.
Flowers are simply different than your normal photography situations. I mean, sure, you might be able to put in a wee bit more orange/yellow to make a day-time shot looks as if it's shot around sunset... but there are simply too much colour variation to handle for flowers.
To illustrate my point - this is a pic of the flower show that I brought my camera to, shot from up to down.
http://www.freeimagelibrary.com/images/amoki/img0303.jpg
There is quite a lot of "stalls" obscured by the lay-out... and because I was shooting from above from a veranda, the details below was pretty much left-out. The show was simply just massive. Unless you have a pretty good memory to remember the colour of every orchid under a pseudo-tungsten lighting (It's tungsten, but less powerfully orange), it's pretty much impossible to fine-tune using RAW.
While the WB on the Canon is great for most photography requirement, in a flower show its completely different... WB bracketing wouldn't cut it because it'll eat up a lot of space unless you brought along a few CF (I only have 1 1GB- damn expensive here in NZ), and the best way to go is usually taking along a white piece of paper for custom WB - which isn't terribly convenient unless you're 1) a nudist or 2) you like people staring at you

. Alternatively, you can go with flash and use flash WB - but you're not the only people with cameras around. (ON this particular flower shot even people as far as Australia and New Caledonia came.)
I said that Olympus camera would have been great during my situation - and only that particular situation - because at least you have an idea what colour temperature correlates with the shot that you want using a meter. However, Olympus cameras isn't any better or worse than a Canon on an exprienced photographer's hand. :hug::