Windows programs (desktop programs, not Metro programs) don't all handle scaling with high DPI displays as well as on Mac OS X, so if you have poor eyesight, you might want to stick with full HD 1920 x 1080. The UHD displays result in tiny text and even with Windows scaling set to 150 or 200%, some programs ignore scaling and still have tiny menu text. Sony Vaio Ultrabooks and convertibles have really lovely and sharp full HD displays, and the Samsung ATIV Book 9 Plus and Asus Zenbook UX301LA are high DPI models (if you still want to go that route) with a great display. The Acer Aspire S7 and HP Spectre 13 have lovely full HD and UHD options too.
-------------------- Lisa Gade Editor in Chief, MobileTechReview