Of the Crank Brothers pedals, several models (particularly mountain bike oriented models) have a platform around the eggbeater clipping system. This helped me learn to clip in. I could place the toe/ball of foot area of the shoe on the platform, slide it forward, and engage the clips. Practice sessions on a stationary trainer were VERY helpful.

I use the Candy model, but their Mallet model has the largest platform. Since the clipping system still is slightly above the surface of the Mallet, I do not know if you would want to use it as a platform pedal for anything other than a short ride. I think the Shimano model mentioned above is the only clipless pedal that is a true platform on one side and a clipless pedal on the other.

However, if it is important to have a platform option, almost any SPD style clipless pedal can be made platform on one (or both) sides with the metal Winwood Decksters Pedal Inserts at LINK. I have not used these, but I see no reason they would not work well for casual riding. Winwood's instructions have some important information on them at LINK. You might also try searching these forums on the Deckster Pedal Inserts.

The best approach I can think of is a good local bike store that would let you try clipping in to different systems in the store with the shoes you use.