I pack my laptop because of photography.

Neither an Air or ultrabook with SSD or iPad or any tablet is sufficient for that.

Where iPad is handy is that if you're away from the hotel all day, there are down times when it's useful. I've used it on long train rides for instance and used it on long flights.

Even in some hotels, I can let my laptop process my RAWs and do some browsing on the iPad. I could do it on the laptop but the photo software will peg the CPU when it's processing a couple of hundred RAWs.

Of course there's a big gap in battery life vs. power, each having pros and cons for different uses.

Taking iPad through flight security adds a few seconds to pull out and put away. It's in an adjacent pocket to my laptop.