I get roughly 3 hours consistently out of my AW 14. Nothing stellar to say the least. If you are looking to travel a lot with your machine, consider getting one that is designed for longer life first, and not necessarily gaming performance. For a short while I was on a Sony SB 13" machine, that could play games fairly well (720P display - wasn't too hard), and had a 6 hour battery life, plus a sheet battery. It used a mid-level AMD video card, and worked out quite well.
As for Asus + Origin VS Alienware, I will say this. They compete on Price and performance. The difference in how they are made is night and day. Both are plasticy machines that suffer from excessive flex, and bending. The Alienwares are mostly metal, have a strong, rigid frame and a solid keyboard.
No matter which company you go with, pay extra for the best display you can afford, and the best GPU. I would not worry about the CPU too much, as long as you have a current quad core chip (4700 and above). The ram and hard drive is better off being upgraded after you buy the machine.
Laptop: Alienware 14 : Intel i7 4700mq : 8GB ram : Nvidia GTX 765 : 256GB Plextor M3 : 1080P IPS display
Test rig: AMD Phenom X4 955 @ 4.0Ghz : MSI 970A-G46 : 8GB Ram : 128GB Plextor M5s : 2x AMD 5770's (Flashed to 6770) : PC Power and Cooling Silencer 750 : Pioneer BR
Hackintosh : Gigabyte GA-H61m : Intel Celeron @ 3Ghz : 8GB ram : EVGA GTX 550Ti : Patriot Torx 2 64GB : Silverstone Strider ES-50 : OSX Mavericks