I’m using Windows 8 on many different devices, but have a couple still running Windows 7 for one reason or another (main family computer has 3d and Media Center – haven’t upgraded it yet). Here’s one thing I miss when I’m not in Windows 8 – multiple taskbars on multiple monitors. In Windows 7, when you extend the desktop you get one screen with a taskbar and one (or more) without a taskbar. Windows 8 allows you to not only have multiple monitors, but make a lot of decisions about the taskbar for each monitor. I love the control and power this provides. I picked up a secondary USB displaylink monitor for $100 – it makes a perfect second screen and is light enough to travel with.
Along with this is the Windows Key + Prt Sc feature – on multiple monitors it takes a shot of everything. Great for capturing a screen or two to send to someone with a question, documentation and blog posts!