Hi Tony, lovely shots.
I've tried my hand at a few HDR's and have had some nice results...some disasters too. For these sort of shots (sunsets) I've starting using a graduated neutral density filter to darken the skies and try and get it in one shot. The problem I've found with HDR is movement, especially those darn clouds, they just wont stay still.
I meant to ask whether you've found Photomatrix is better than the HDR merge in CS3?
cheers,
Rob