Karnak is indeed pretty amazing! I could spend hours wandering the Hypostle Hall -- with all those towering colums -- and never get bored. (Have you seen Agatha Christie's "Death on the Nile"? There's a great scene that takes place at Karnak...)

What you noticed about Luxor vs. Giza is perceptive, and is the result of many, many years of conflict between the government and local residents in both places. It's an interesting story, but it boils down to this: Years ago, there was an attempt in Luxor to relocate west bank residents to a different location, away from the tombs and temples (you no doubt noticed that lots of people live right in the middle of everything). This attempt failed badly, resulting in serious violence between locals and the police. The resulting stalemate has left everyone happy except the Egyptologists. In Giza, however, the issue has never been forced as directly, and the result, oddly, is worse: Whereas the tourist-fleecing industry in Luxor is pretty seamless but harmless, at the Pyramids there's no control at all. The real power there is vested in the townspeople of Nazlit ash-Shams (if I rememer the name correctly). The pyramids are their cash cow, and they know it. They also know that the government can't risk violent clashes right in front of the biggest tourist draw in the country. So there's no control over the hawkers.

Anyway, if you were able to appreciate the pyramids even for a moment, you get how splendid they are...

Congrats on a great trip!