I shoot "Adobe RGB (1998)" now UNLESS I am shooting for the WEB only. The color gamut on Adobe RGB is much wider than sRGB. You cannot really see that on your monitor, but you CAN on paper when printed on a LightJet or comparable technology.
So, my rule is:
For Printing, use D100 Mode 2: Adobe RGB (1998) For Web, use D100 Modes 1 or 3: sRGB