Awesome, thanks for the tips guys. I have booked. I will have 24 hours in the following:

LAX
SIN
IST
BUD
PRG
FRA

Any tips on what to see? I realize it's a short amount of time, but if I can get in 1 or 2 must sees, I would be happy.

Also, as a solo traveller, are all these safe?

And stopping in BKK, is that safe? Hotel or hostel?

Oh, and in Business class, do I have access to lounges with showers, beds, etc?

YYZ-LAX-SYD (4 weeks)
SYD-SIN-BKK (2 weeks)
SYD-IST-BUD-PRG-FRA-FCO (4 weeks)
FCO-YYZ