If you store a lot of music, books or pictures, and if you have a lot of Docs on it, then you might want to go to the larger gb versions. I went with the 32gb. Only $100 for double the storage.
For Work:
Excel spreadsheets
Word documents
PDF files
Personal Use:
Pictures
Music
Videos
Once you get it and see how great the videos made on the PlayBook are you will wish you paid the extra money. I took a short video. 30 seconds in front of my house and it's almost 30mb. That's not to say if you make a lot of videos that you will leave them on your PlayBook. I also have regular videos that I converted and they are 2-2 1/2gb each.Currently I have 3 plus some videos I haven't redone.
In total I have the following:
9.24GB of video (16 videos)
4.94GB of music (715 songs)
58.5MB of pictures (252 pictures)
33.45MB of documents (432 documents)
I'm using 18.1GB of my 64GB. That 18.1 will go up as I convert the videos I have to a higher quality.
So what I am trying to say is buy as much as you can afford.
64 GB:
30 GB music
13 GB video (varies as i watch and delete and add)
.75 GB photos
.25 GB documents (personal writing, role playing gaming material)
10 GB free