Peggy Lynn,
Do not go with Speedplay. Why? You will need to deal with a new peadls system including cleats. SPD style I highly reccomend as they can easily be found anywhere.
Also the Speedplay pedals offers quite a bit of movement that many people simply dislike as it takes much more rotation to release.
I suggest buying normal SPD style pedals. The ONZA pedals are great but cleats are somewhat hard to come by these days.
I personally do not like Speedplay and I will say that straight out. Product is OK, nothing execellent. My bad experience comes from their serice to me years back. It got very personal with them.
Lightness is a thing people say but look at the cleats as those are heavy as that is where the mechanism is attached.