Shelby,
If you're planning on doing much walking with a Backpack, it's very important to make sure that you're properly fitted according to your torso size. Most of the weight should rest on your hips, NOT your shoulders. While overall height is a good estimate, it doesn't always accurately reflect torso size.
Given your height I suspect the RS Convertible Bag would probably work for you. You might send an E-mail to Rick's office to see what recommendations they might offer. Incidentally, I believe the Convertible Bag is supplied with several of the RS Packing Cubes.
You might also check out the Eagle Creek line of Packs, as they have a number of models in different sizes, including some with harness systems specifically designed for women. I can't comment on the E-Bags models, as I've never used them.
Some of the features that I look for in Backpacks are a "stowable harness system" (harness is stored behind a zippered panel during air travel, so straps aren't torn-off by baggage handling equipment), a detachable Daypack (works great for carry-on when the main Pack has to be checked), a "shower cap" (great for those unexpected rain storms) and finally a panel-load design (which uses zippers rather than a drawstring at the top, which is more convenient to find contents inside and zippers can be locked providing a minimal amount of security).
Good luck and happy travels!