SPD-SL's are good for road riding, and are good for using as platforms with regular shoes since they're wide and long.
Toe clips are good for commuting and short rides, but suck for long rides because you can't get max power and because your foot won't be in the right position over the axle because they're hard to adjust that way.
Platform-only pedals don't belong on a road bike. Save that for cruisers and comfort bikes that you ride short distances to get around.