I replaced the 9005/9006 bulbs with 9011/9012 (7500K/8500K). It's a cheap and easy improvement. The tabs need to be modified, easily done with a Dremel and this guide; How to Modify HIR bulb bases
For the fog lights, I replaced the OEM 899's with 885's (50w). This is a plug and play swap. There's a healthy increase in brightness, without stressing the existing wiring.
The fog lights need to be re-aimed, since they are WAY too low from the factory. You can do this yourself, garage door in the evening method. Turn on your low beams, and mark the top edge of the beam with some tape. Turn them off and now turn on the fog lights. Adjust the height of the fog beams to match the top edge of the low beams. You'll find thereafter that driving during the dusk/dawn times, you won't even need the low beams, just the fogs will be fine.
Finally, the hi/low beam relay kit. I added this as well. When using the high beams, the relay kit keeps the low beams on as well. This gives you all four eyes on the road.
Note to self .... always let the Hummer lead the way and never drive towards it with ANY lights on...just in case.