Two HDD bays are the best configuration for a laptop, I haven't been able to find that setup under a 17", and usually the higher end versions.
My Dell Studio 17" has two bays (SSD and HDD
) Dell's only new model with 2 bays is the XPS 17". At least from what I can find. All OEM's don't make the drive bay specs easy to find.
With SSDs becoming more popular dual bay laptops should be showing up in smaller models, though the new 'Thinner is better' trend may prevent this from happening.