Lots of great suggestions. Nikon also has a new entry level P-223 series of scopes. 3-9 BDC and Rapid Action Turret mark with distances to 600 yards and a new 3X scope for those of you who have good eyes and like to shoot with both eyes open. Good scopes built on the PROSTAFF platform. They were very well received at Shot Show last week. The M-223 1-4 Point Blan Reticle will do great to 200 yards. After that my eyes need 2-8 or my preference 3-12 magnification.
Also, if you want to swap out scopes, I think Larue makes excellent QD mounts. They are also $$, but if I am buying a set for my rifle, that is what I am getting.
Here's a pic of the new P-223 3X Carbine Scope.
http://i1216.photobucket.com/albums/...-223DPMS3X.png