I'm ordering the Spyder 3 Elite as I'm getting a projector for the home theater as well. Going to try it on that as its not offered on the Pro.
I sent a few of my photos off to a print house and they came back, less then I was expecting. So I started doing research and found ColorVision's Spyder series.
I figured if I was going to print out 16" x 20" photos I want them looking the very best. I have read that its a good practice to check it on a regular basis or before you start doing alot of color corrections. Also make sure that you calebrate it to the standard that your print house uses. You should be able to find out if they use sRGB or Adobe RGB. They make a huge difference if you send them the wrong files.