I'd much prefer 500GB for the same price that I can use to share our collected documents with one or two people in my immediate family without having to pay for the same space again for each of them. Dropbox for Business is too expensive, Dropbox Pro is too individual.
I'd recommend Office 365 Home Premium. It includes 5 user accounts, each getting 1TB of OneDrive storage and access to the full MS Office Suite. The retail price is $99/year, but you can typically find discounts, e.g. here it's $70/year http://www.bhphotovideo.com/c/product/917386-REG/microsoft_6...
The native integration with Windows 8 is also quite nice. If you're not on Windows it still might be worth considering just based on price alone (especially if you use MS Office).
Dropbox Family, please!