My final year project is designing a power amplifier with a bias control network and an open loop power control system.

The system looks like that:

The 2-Stage PA looks like that:
http://www.electro-tech-online.com/...-power-amplifier-system-design-pa_2_stage.jpg

Firstly, I'd like to focus on the 2-stage PA itself, disregarding the bias network and OLPC system.

I'd like to bias it in class AB.
My main goal is to maintain high efficiency.
How do I start?
What kind of simulations shall I run?

The PA should maintain an output power of 1W.
The input signal frequency is 5.8GHz.

I'd appreciate your guiding folks.
Thanks.
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The main difficulty with building a 5.8GHz amplifier is the layout. You must use stripline PCB traces and careful control of all parasitics. If you don't have it, I strongly suggest you find a layout program designed for microwave circuits that calculates the stripline parameters and other PCB parasitic parameters. And all devices, including the packages, need to be designed for high frequency use.

You then use those parameters to simulate the circuit using a Spice type simulator. A simulator designed for RF/microwave simulation would be best.

You are taking on an ambitious project.