I have finally formulated a solution for the "sharing families". Please comment if you find inaccuracies or if you can enhance this solution.
1. Mail, Calendar, Contacts, and Notes:
Since 2 years before iOS 5, we have been using some of the functionalities seamlessly across the family. Seems like, we will have to continue with this set up. We have been using what Neil Trodden describes in this answer. Establish a "family shared account" on sites such as Google, Yahoo, etc. (we use Google) for mail, calendar, contacts, and notes. PS: Contacts and calendar are set up as "Exchange" and the mail and notes are set up as "IMAP". Works like a charm -- as soon as one device adds/updates a contact -- all others have the latest! Calendar entries show on all devices instantly so that family engagements are never double booked and grocery lists (and other notes) are instantly updated across the devices. Hassle free, hands free, as it should be.
Besides the "family shared account", we each have our own employer's accounts (email, calendar, contacts, etc) that are setup the way the employer's systems want. Any additional personal emails can be setup the same way.
2. Music, Apps, Photos, Documents
If a family does not share these, what else will they? If you think of 5GB times 4 devices = 20 GB free, that is the thinking block. Just set up 5GB times 1 free account and enter that information into all devices. The devices will happily share the photos and documents. You probably already had one iTunes account with credit card etc for app purchases, you might as well use that same id to keep things simple.
Now one would ask if single ID works for these 4, why not use the same for mail, calendar, contacts and notes? Answer is you could if 5GB is sufficient for 4 or 6 people. There is some complication about iCloud trying to copy all email accounts to other devices and interfering with the employer's appropriate use policy if you have employer email/calendar showing on one of your devices.
3. Bookmarks and Reminders:
I have found no way to conveniently share the bookmarks across devices/people. I guess search engines are good enough for the job; we don't miss this much. As for the "reminders", the real question is -- why are they outside of the calendar? Apple should have kept it simple.
But that was in paper world, one could argue that both apps bell you through the same device, so the system still works if you have one device. I don't yet know if reminders will work through all devices.
Apple considered a cloud of devices while designing iCloud, but a lot of us are a combined cloud of devices and people. I guess they were in a hurry. Hopefully, there will be added human cloud consideration to a future version. Trying to automate across this simple scenario is the first. Next level will be to deal with the fact that each of us is a point shared in multiple people-clouds (e.g. family, work, professional circle, PTAs, etc.). Automating across that scenario will require the end users to grow up to the challenge.
Any comments on this set up would be appreciated. Your comments will help, as I am considering adding a couple of devices for additional members of my family who will join this man machine cloud soon. The point is to keep it as much hands free as possible in a most economic way. Good products Apple!