Thanks to everyone who has contributed to this thread. Some of the comments have been very thorough and were helpful to myself as I'm sure they were to other readers.
I've narrowed my choice down to a S&W 66 (P&R) and a Colt King Cobra; both in 4" barrel. Both are classics; both look beautiful; and I would expect both to work very well. I believe the Colt is slightly heavier (L frame?). The S&W would probably feel more familiar to those used to that make.
Can anyone add any last thoughts as to why one might be preferable to the other?
PS. To those suggesting other makes/models; there is a plethora of great guns in this class and at some point I just have to chose and more forward