My husband and I have three younger kids (9, 7, and 5) and we like to take them backpacking.  My pack is 15 years old and I'm about ready for an upgrade.  I'm also considering purchasing a pack for my 9 year old.  Would you please advise as to what size pack I should buy both for myself and my 9 year old? 

We have pretty standard backpacking gear: down/synthetic down sleeping bags, sleeping pads, etc. We have to carry two tents (a two person and a three person) and two bear vaults for the family and our dog.   So the amount of gear we carry adds up fast. 

Thank you!