Hey,
I have problem with creaks, noises on SPD pedals - for a very long time (few years, beginning from MTB). There are some creaks during rhytmic, calm ride, especially on road... it devastates road driving pleasure
I have two bikes and one shoes for them:

1. Cyclocross bike with PD-M540 - creaks are not issue here, it's "wild" ride
2. Road bike with PD-A600 (single-sided SPD)

And shoes: very good and very comfortable for me, Shimano RX800 - stiff and lightweight, I like them.

I tried to use chain grease on SPD cleats, I tried finishline spray for SPD - it helps, but only for max. 1 ride... after that, there are creaks again.

What can I do with that?
I consider to move to SPD-SL but you know... I will have to buy pedals and new, similar shoes, and I will gain nothing more, so it will be quite expensive fix