Recommend me a photoshop-capable lightweight laptop

Though it covers a little of the same ground, this is not quite the same as Mystic Violet's question (no interest in touchscreen here).

Based on our recent experience in the land of Mex, we need a new laptop. The needs are:
- Able to open & review photoshop files. Wouldn't need to do heavy duty image creation/manipulation, no need for colour accuracy, just able to open, review and markup complex .psd files.
- Lightweight, 15"-ish screen. This is not a desktop replacement.
- Battery life suitable for Arizona to East Coast flights. Call it 5 hours.
- Able to run 3D games, but we can turn the detail down, so I think almost any half-decent discrete graphics would work.
- This will be used in front of clients, so needs to look professional & stylish.
- No firm budget, but less $ for laptop cost means more $ for games!

We had just started looking and found the HP Envy 15, Dell Latitude 15 (i5-430M), Lenovo Ideapad (i5-430M plus 1GB 5730). Any thoughts?