I did my fogs with HID's, too, and it makes a ton of difference. If you do it in the OEM housings, don't run them in traffic, though. They just spray light everywhere. I've since retro'd a set of projectors into my fogs, and they have a pretty good cutoff so other's aren't effected too much by whether they are on or not.
For the High's I'd recommend getting a set of HIR bulbs.
http://www.amazon.com/Philips-HIR2-Standard-Halogen-Headlight/dp/B00480N18G They are the brightest halogen bulbs out there. You maintain the instant-on and flash options with your high-beams and add a lot of light. If you want max high-beam light, do the 6-high mod.
http://www.tahoeyukonforum.com/forum/showthread.php?t=571
I should add that the HIR bulbs are bright, but they are a bit more OEM yellow in color, so they won't match HID colors exactly.