As a general rule of thumb, your "stuff" will expand to fill all available space. I do play games, I like those hidden object ones, scrabble, solitaire, sudoku etc. I also watch videos and lately process photograps.
Essential apps for photography/processing.
Snapseed by [?] - Download Snapseed in the iTunes App Store
App Store - PhotoForge2
App Store - Pixlr-o-matic (free)
There are many others, too many to list here, its a matter of try, and buy if you like, where there are "lite" versions available.
Video Watching
CineXPlayer (ipad only)
OPlayer HD for iPad on the iTunes App Store (ipad only but there is a version for iphone as well. not a universal app)
Games
Scrabble, Taptap sudoku. Plus a bunch of bigfishgames hidden object stuff. But only if you like that kind of thing.
I have a keyboard dock and never use it. I might use a keyboard if it were built into a case, but then again, might as well use the MBP.
Bought a pogo sketch stylus. Its OK. I hear the griffin and targus ones arent too bad. Whichever you were to choose, be prepared for a different experience. Of necessity the stylus has a lot of "drag" because of the nature of the touch screen. I used mine to take notes in Rounds at the hospital when I was still working. Couldnt tell you where it is right now. It would be useful if you were into drawing with apps like:
ArtRage for iPad on the iTunes App Store
App Store - Adobe Ideas (free)
Brushes
I've used the stylus with
Penultimate for iPad on the iTunes App Store (my favourite just for random notes)
Managing your ideas, taking notes etc...
ThinkBook - Write, Plan, Outline and Take Notes for iPad on the iTunes App Store
I guess I have spent well over $800 in the app store, not just on ipad, but also on iphone stuff... Much of it I have deleted. Here's the thing.. if you can get a lite version prior to spending any money... do it!
Oh... Pages is pretty good and if you are iclouded and have it on Mac as well, its syncable through the cloud.
I made a really long post on my blog when I first got the iPad. You might want to have a look at that too, just for an overview from a user, keeping in mind that the post is over a year old.
20 cool things to do with an iPad « Hamarana
I plan to upgrade to iPad 3 when its eventually released, I think I'll do that before I u/g the phone. Next time around I will be looking at going 64G wifi. I currently have 16G wifi only. I use a mini wifi router thingy because I have many portable devices and if I am out and need that much internet, I'd rather have something in my pocket that I can use with my laptop and phone as well.