When you are visiting Cairo, you should skip the noisy, overcrowded, full-of-hasslers 9 Pyramids of Giza and visit these nearby Pyramids instead (there are approx. 99 Pyramids in Egypt)

Pyramids of Dashur (one hour south of Cairo - 20 minutes from Saqqara)
Dashur is a snapshot on what Pyramids of Giza looked like 50 years ago before it was overwhelmed by blatant commercialism.

Red Pyramid of Dashur. This Pyramid is awesome. Go inside and explore the three chambers in peace Indiana Jones style - beware of the stale chamber air though.

Bent Pyramid of Dashur. This is how a Pyramid look like when the engineers realized their mistakes and tried to fix it. This Pyramid is 8 minutes away from the Red Pyramid.

Pyramids of Saqqara(20 minutes from Cairo)
This site is receiving more attentions from tour operators nowadays but still is a much peaceful place than Pyramids of Giza.
Step Pyramid. This is the oldest Pyramid ever (I think it's 5000 year old). If you visit the site, do not forget to visit the nearby Ti Pyramid that actually looks like a hill of rubble. The chambers of Ti Pyramid are the most decorated chambers of any Pyramid I've entered in.