Should I wait to buy an ultrabook?

Hello, so I'm planning on buying an ultrabook and this HP Envy Sleekbook and this Asus U36SG-DS51 seem to be good choices, but I'm still looking and definitely open to suggestions for something in the 600$-800$ price range.

But I was wondering whether it would be worth it to wait for newer models to come out with higher-end technology? Can you predict how long I might need to wait? Are deals that take into consideration the beginning of the new school year common with laptops/ultrabooks? Thanks.