Use multiple themes on one installation

Hi

I have tried searching for this on my own but couldn’t get a clear answer.

I am a website developer. I keep needing to switch between mutilple wordpress themes in order to get client approval.

Is there a simple way to do this without requiring to repopulate content in the new theme each time ? I tried enabling the network option on my base wordpress installation but I couldn’t get it to work.

What is the best way to do this ?

Thanks

PJ