Your displays are what holds many of us back
As some others have requested, a matte screen is a must. It is, for many of us, one of the few features that could qualify as a "sine qua non" for any laptop to be used that often.
The last Dell I bought for development was an Inspiron 6000. 3 years later, I bought a MacBook Pro and have been holding onto it because Dell simply will not offer matte displays even as a premium option on XPS and Alienware systems.
Right now, if that 4 year old MacBook Pro died, I would likely buy a Samsung Series 7 laptop because they have good specs and come standard with respectable matte displays.
How much is this feature worth to me (and probably many other here)? Apple charges about $200 for it on all 2011 and 2012 MacBook Pros. I would gladly pay that much to Dell.
I understand that many home users are content to use a glossy display in a dimly lit room. What I can't understand is why so far Dell has dropped this on every system where it could be a premium add-on.