Which Dell Monitor setup to buy

[bumzo1]

I'm going to buy a gainstown Mac pro once they are released and looking to update my monitor setup as well. I plan on buying dells because they are good quality and cheaper than ACDs.
My options are:
2x Dell 20" utrasharp
1x dell 24" ultrasharp (and buy another next year if I feel the need)
1x Dell 30" ultrasharp refurbished (buy another if I feel the need)
I want the most screen real estate for the $ but in the end I want no more than 2 monitors on my desk. So if I buy 2 20" now I won't buy any more in the future. I also want the screens to all be the same size and not mix matched.
So, What is my best option?
Thanks

 

[numbersyx]

Dell 24" for me. Can't get too much of it but this is better value than the 30 esp. if you can buy another next year.... Have a Dell 24" and am very happy with it.