I take far too much camera equipment, but not really a great deal of hand luggage.
I found the perfect solution for the last trip in September and that is the Lowepro Orion Trekker back.
http://www.lowepro.com/Products/Backpacks/classic/Orion_Trekker.aspx
This is a very compact rucksack that easily accomodates your basic hand luggage needs as well as having suitable storeage for camera and equipment in a seperate compartment.
It is pretty well padded and I got my Fuji ditial camera, Sony video camera, all batteries, blank mini DVD's and memory cards in with ease.
Everything is very well protected and it travelled with ease.
I used the bag every day in the parks and it was a very useful way to carry the stuff round as well as having a suitable amount of space to carry basic day-pack stuff (drinks, tickets etc).
Ironically, I may have one of these for sale soon, as I have received one as an introductory gift.