I feel like posting in this thread even though I don't own a tab
My iPad 2, I take to work most days in my briefcase. I generally watch 20-30 minutes of a movie, a short TV show or part of a longer one, maybe play a bit of a casual game, what not on my lunch break.
My nook simple touch also ususally comes with me. If the weather is crappy outside instead of walking the last half of my lunch hour I'll read for 30 minutes. Also later in the day if things slow down and I don't have much to work on, I might read at my desk some as well. Probably average another 30 minutes of reading if you average out all the days.
My nook ST is just small enough with its cover to fit in pretty much all my jacket pockets, so it comes with me most places if I am going to be out and about for a day or if I don't want to take my briefcase to work. iPad 2 is just too big for that, and at least looking at one, a nook tab/color also looks like it would be just a bit too big to carry most places for me.