Apple didn't do a good job of explaining iTunes ID vs. Apple ID over the years but I use a shared iTunes ID and individual Apple ID's. This way everyone gets their own contacts, calendar, Photostream, iCloud 5GB, etc. but we only need to purchase music, apps, etc. one time.
Not only did Apple do a poor job of explaining this, they did a poor job of implementing it. I want to share all of the things I highlighted in bold, while keeping actual "personal" things separate (bookmarks, email, per-device backups, etc). There are ways to share the first two, but the photo stream is locked to the primary iCloud account only. Thus in order to share it seamlessly, all family members must use the same primary account, giving up personal syncing of bookmarks and separate 5GB for device backups.
That's my biggest gripe with iCloud. Apple assumes one person per device and per iCloud account. There must not be many married people working there, because I'd think that photo stream sharing would be very popular among families. And no, the stupid Facebook-style shared photo streams doesn't cut it - that's not automatic like the primary photo stream.
I love that any photo I take automatically shows up on my wife's phone, and vice versa; and they all show up in my iPhoto library which is our central repository for family photos. But we give up the ability to keep our device backups separate, and thus the removal of the free 20 GB storage impacts us more than those who only have one device on their account.