I think you need separate, Mac OS Accounts.
Once you set up two isolated Mac accounts, and sync your iTunes with your iOS devices, and setup separate iCloud accounts etc. email accounts etc things will be fine.
But one computer, with one login account, with both of yours and hers stuff just dumped into iTunes, email, bookmarks, iCloud, Documents, would be a nightmare...
EOL
I'd love this. Clearly it's what Apple wants us to do. Reasons I still can't:
1) Who 'owns' iTunes? Yes, you can share music but only one of you can edit the library. The other is a second class citizen who can't rate songs and alter playlists. So one of us is the music master and the other is treated like a child. And good luck getting your iPad to sync with iTunes tonight, sweetie. We left the Mac logged into the my account all night so that MY phone can sync. Sucks to be you.
2) Who gets the photo library? Whoever doesn't can't have access to it in other Apple programs that tap into iPhoto and they can't quickly find shots to send to e-mail or to use in photoshop or anything. Whoever loses this coin toss is pretty much SOL when it comes to our thousands of family photos.
Yeah, you can open the library, but is having 2 versions of a database software accessing the same database really a good idea? Everyone I know about computers says 'no.'
3) Also, that nice trick where photostream downloads every iPhone shot into our library AND uploads our SLR photos
back to every iPhone in the house?
Yeah, screw that now. It was nice while it lasted.
4) Who gets Final Cut Pro and the home movie clips? Just like #2, you COULD open it twice, but get ready for disaster!
5) Oh, and btw, when the iTunes owner is streaming a movie to the Apple TV for our daughter THEY can check their e-mail and surf their bookmarks. The other person? No such luck.
Too bad for you!
6) And to mix 3 and 4 together...
"Sorry, I'm exporting from Final Cut Pro for the next hour. You can't use your bookmarks until it's done."
That's just off the top of my head, I know there are other reasons I can't remember right now. Basically, Apple's position is
"You should use different accounts but we will never make our software work with that workflow! Bwa ha ha ha ha!"
The bottom line: Sharing an account gives me 4 or 5 headaches. Splitting up would give me a dozen. Thanks for this awesome choice, Apple.