If you're in southeast asia you should consider a swing into Siam Reap, Cambodia. There are hundreds of ruined (some rebuilt, some not) temple complexes there including one of the wonders of the ancient world,
Angkor Wat, that sat swollowed by the jungle for 500 years.
The scale of the structures, the level of detail in the bas-reliefs and the amount of access to ancient monuments are unrivaled anywhere I've been. The town is safe (basically built to accomodate tourism) and you have a range from disneyesque hotels with pools to 10$ a night places that are perfectly servicable. We toured temples for 3 days, hiring a guide and a taxi driver for day 1 and just the driver for the subsequent days.
This place made the Pyramids seem so-so.