Since I started this thread, I guess it's time to chime in again. I think I'm leaning to getting clipless, but mainly for what I believe will be to make the pedaling effort somewhat more efficient and easier. I'll never be a speed demon or particularly competitive, so that's not my motivation.
If I take the plunge, I will likely get those dual pedals with clipless on one side and flat on the other, and MTB shoes. I appreciate all the input here.