I agree with you. While the vehicles were actually interesting, the buildings looked just like something that was designed in minutes to get a building for the set.
Other reasons Pharao's Quest failed, may be the lame storyline, that was basically just running from one treasure to another and fighting mumies, no searching for and discovering ancient ruins, evading their traps and find the secrets.
I think the primitive stories the Adventurers comics back then were good. They told a story without completley limiting it. I think letting the adventure take place in modern times would be better than nothing, but some kind of charme would be missing.
A good theme could be the search for El Dorado, the City of Gold. The hero team should be composed of very unique and different characters, that are still kind of equal.(think of Jonny Thunder, and his crew)
The villains could either be some kind of "Dark Power" a brotherhood of gentlemen, who believe in supernatural forces and want to gain world domination. Or they could just be a ruthless treasurehunter and his followers. Thy got the support of the locals. This would give us an interesting storyelement for the older, while for the younger, they are just other villains.
Maybe there could be dangerous animals and guards of the ruins too.