Hardest decision of my life.

Hello.
I have an REALLY LARGE project going on. i am working for an company and i will receive 50% of the income we generate as i set up the website.
but it is an really large. REALLY LOADED website. compare it with trivago.com same base
So here comes the decision:
What hosting do i need for such an heavy project, which i was told maybe needed an multiserver installation. is windows azure good, or just bad an way too overpriced?

THANKS!!!!