Still happy with Office 2010, which I got for $20. I'm not sure what additional features 2013 provides, but there's nothing I can think of that I just gotta have. Otherwise, I'm not opposed to using OpenOffice.

Does Open Office or any other open source alternative have anything comparable to Outlook yet? It's the only reason I'm tied to Office. I use calendars extensively in my business and nothing else I've tried has come close to it in terms of maintaining and editing multiple calendars.

I would love to ditch it in favor of something else to escape Office. I have it synced to Google calendar which I access on my phone, but if you have any heavy calendar editing to do it just doesn't cut it (can't even copy/paste events or select multiple events).

thunderbird with the lightning/calendar add-in is the closest i've found to outlook, haven't tried syncing it to google calendar (though thunderbird itself handles gmail fine)

I use as my main office platform Wordperfect Office. As a backup to it I also have Libre Office. Libre is outstanding.  

FOr those wondering about Libre Office, it is a fork of Open office.  The developers of open office were concerned Oracle was dropping support so they left.  Orsacle abandoned Open office which is now run by Apache.  Most Linux distros use Libre now.