Not sure if this topic arised in any old post or not. Coz' there is too much to browse thru them all. but anyway, here i go.
The only must-build is Sistine Chapel. The bonus is way too important (double effect of cathedral) and it doesn't obsolete.
I always play R civ. so cathedral is only 80 shield and i build them even in cities that wont grow beyond 12. Save me a lot of trouble with having disorder! not to mention i can even have WLTKD during war while using Democrazy

as my gov.
I haven't tried the 2 hardest level yet (i hate to lose

) But racing wonder with computer after the 2nd age is easy. I usually build everything in the last 2 age without a sweat (worrying that computer might build it 2 turns b4 i complete my wonder, especially when i have nothing to switch to!). (xcept that i dont build Mahattan Project and United Nation)
Needless to say, the Fobbiden Palace is way in the lead in small wonders. Or am i wrong?