Here are a couple of examples:

1) On the plane, if I want to relax my tablet (these days usually an iPad) goes in the seatback pocket. I'll catch up on a book via Kindle, read the WSJ through their app, or read RSS feeds. There are no good "standard" Windows 8 equivalents to these apps (except perhaps Kindle), since desktop apps are designed for a connected, keyboard/mouse-driven experience.

2) In meetings, I use the iPad as a digital notepad. I know many people use their laptops to take notes, but I find this diminishes the client interaction (ever try talking to someone while furiously pecking away and staring at a screen)? A nuance perhaps, but 95% of my job is interacting with people in a small conference room setting, so this is a major factor for my type of work.

I use the laptop for standard business tasks: spreadsheets, email composition, document creation. The tablet doesn't do this well, but does the above tasks so well it's worth the space in my bag.