I've tried the mountain and road style shoes and pedals but now use only the mountain bike style. I prefer them for their ease at walking in restaurants, rest areas on organized rides, restroom stops, etc.
I have Shimano M540 pedals on one road bike and Shimano M324 on the other road bike. I use the M324 with clip-in on one side and a regular platform on the other when riding with a biking program where there's a lot of stop and go riding. I also use that bike for errands or short rides around the neighborhood when I wear regular clothing and shoes.
As others have said, be sure to try the shoes on for size and fit before ordering from the internet.
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Enjoy the little things in life, for one day you may look back and realize they were the big things.
-- Antonio Smith