Our family has two iPhones and two iPads and a MacBook pro. With iMessage it for the most part works well. I am starting to grow tired of apples way though and I will try to explain. We all share same Apple id for app purchases and music purchases. By doing that Apple makes it almost impossible to keep devices separated! All of a sudden I will get iMessages from someone else's device for example! My main problem though is with pictures! We have lots of pics of the little ones running around. Apple makes this so hard to save them! Yes you can use iCloud (which I don't like) and you can load them in iPhoto which filled our computer. We had to switch to an external drive for iPhoto library. Which makes loading pictures a nightmare! Has any one else had this and made the switch to android? If so how did the switch go? Sorry for the long post I hope a few will take the time to read!
Just stumbled across your post and I'm neither Android or iOS fan I own both i'm a technology fan so I'm not trying to lure you anywhere as I own devices from both sides.
Your comment about iMessage and itunes store accounts is incorrect or no one has bothered explaining to you what you need to do.
iTunes store accounts are awesome to share among family members no one wants to purchase the same thing multiple times ever. You can always use that iTunes account on all devices and never worry about being mixed up anywhere else.
There are 4 different locations you can sign into anywhere from 1-4 Apple ID's on every device. Here I'll give you a rather simple explanation to make it work for you how you want.
1. Setting -> iTunes & Apps Store
2. Settings -> iCloud
3. Settings -> Face time
4 Settings -> Messages
Now you can use 1 or 4 different accounts if you chose to whatever works the best for you. Apple ID's are not a per device thing they are a per user thing and always should be.
Sign into Itunes with the shared account so everyone continues to share purchases. Create icloud accounts for everyone individually so they all have their own backup, phtotostream, contacts calendars etc. Use the icloud accounts for icloud/messages/facetime and continue using the store account for itunes purchases.
Now all 4 people can message, face time & have their own contacts/calendars/backups etc and still continue to share all the purchases.
you can have your cake and eat it too!