I find personally that the Crowbar fits smaller while the Splice fits bigger, and the Canopy/Airbrake fits biggest. The Crowbar also fits tighter on the nose than the other mentioned goggles, so if you have a huge shnozer, this may not be the goggle for you. I'd say I have a Medium sized noggin, and mine fit great. Love how interchangeable parts are as well.
Here's mine pimped out with just a few of my extra outriggers/straps that I've bought.
If you want a lens for night skiing go to this link:
http://www.oakley.com/products/3279/10381
And click on clear. If you're doing some night skiing at a resort with really bright lighting, then you may want the gold clear lens, but its $25 more, and the clear one will be wayy better if you plan on skiing in some darker area's.
Good Luck!