How much storage do I need on a new iPad?

I know, I know. It all depends on what you're going to use it for. So, hear me out on my situation.

I'm going to be spending a month in Germany/Europe and am primarily buying the iPad as a lightweight, easily portable entertainment object. I want movies on it for the long flights and train travel times that I'm sure will ensue. I also want to use the camera on it quite a bit (despite how awkward it looks to take pictures with the iPad) so there has to be enough room for some picture storage. There also has to be enough room for a few basic apps (facebook, twitter, etc. No big gaming ones).

So basically, I'm sure I could get away with putting like 5 movies on my iPad and being entertained enough with room for everything else, but it just feels so restrictive and I hate being afraid of running out of memory. So, would you suggest the 16 or 32 GB?

Thanks, guys! I would have asked this in an apple store, but there isn't one close by right now.