Buy better shoes. With a stiff sole, the pedal is almost irrelevant. I've ridden a century on Crank Brother Eggbeater pedals, which are essentially just a spindle, using my Specialized BG Comp shoes and my feet were perfectly fine. My soft-soled Shimano MT31 shoes, on the other hand, start to feel a bit tiresome after 60-70 miles.

If you really have to have a larger platform and don't mind a weight penalty, there are SPD pedals with larger platforms. Look at the "All Mountain" SPD pedals like the PD-M530, PD-M785, and PD-M985.