Any discernable advantage to using a variable power scope on a .44 Mag? I'm thinking it's a 100 yard weapon, 4 power should be plenty.

And which one(s) do you like?

I like leupolds eye relief the best. Go to a sportsmans cabelas etc and check the eye relief for yourself. With a weaver or nikon I have to shoot with my arms bent and off a rest it feels really wierd to me. I have a 2x leupold on my 357 and can shoot soda can and water bottles at 100 yards. 4x should do you just fine at 100.

if your shooting mostly close a fixed 4x can be a little too much power.a variable is a nicer option.

I use a 2x Leupold for whitetail deer and find it to have enough power and a good field of view. I don't take shots over about 125 yards on deer.
I do like a variable on some T/C barrels (.223, etc.) where the shots may be taken at a longer distance, or for varmits.

Yeah . . . I'm putting it on a .44 mag for elk, deer, bear, etc.

If you are going with the Ruger Super Blackhawk, you might be interested in some of the discussions at the rugerforum.com site. Lots of revolver shooters, and a classified section there.