Are you sure the 20D doesn't have the W(edding) function?
I'm sure it has cos I've been using it for quite some time previously.
:dunno:
On the serious note. There are no 'safe' settings in outdoor photography. You can practice for weeks with the "recommended exposure settings" (f/x.x at 1/xxxS using ISOxxx) on endless sunny hot afternoons. What happens if there is heavy over cast or it starts raining (touchwood) you cannot just say the lighting was lousy that's why the pics were lousy.
Excuses are just not acceptable for somebody's big day. Imagine your photographer telling you: "Oh today is not as cloudy as my other shoots, so the pictures were overexposed. But at least can see the face. Not bad right? :sweatsm: :sweat: ".
A polariser can reduce glare and some hotspots off the leaves of the greenery and thus produce "vivid colours" (to some extend). But if the greenery is mostly in the background, it just isn't going to help much (pop up the green saturation in PS is better). Also, the sky won't be any much bluer than it already is becos of sg's location on the globe (you'll need a good=expensive PL to get some effect). It is also mostly cloudy on most days recently (and any part of the year).
Good luck! Hope to see your shots soon.