ebags TLS Mother Lode Weekender Convertible Junior
http://www.ebags.com/product/ebags/t...gs-and-reviews
This is the bag for a trip like you have described. You will need backpack straps if you are walking 1+ miles with your bag.
Also they have a great warranty and if you catch a sale right their price is not bad. I think this weekend they have 20% off.
Good luck!