You won't want to be too high up on the ladder and you won't want to buy a ladder and still be dealing with everything at a reach.
Given that, if you're 5'4'', I would think a 6 foot step ladder would probably be good for things around 9-10 feet up (would put you on the level of those things without having to go too high up on the ladder).
An 8 foot ladder would probably put you on the level of things around 11-12 feet.
You can get to higher things, but you'll either have to go up a bit higher on the ladder or you'll have to reach for them.
I think ours is 6 feet tall, and other than those really high items I mentioned before, I never have had an issue, but I do have to go up pretty high (the last rung made to support a person) and at 6'2'' I have a bit more reach than you'll have.
I'd probably get an 8 foot - probably overkill for most stuff, but it will keep things more on your level without you having to get way up on it.
http://www.homedepot.com/p/Werner-8-ft-Aluminum-Step-Ladder-with-250-lb-Load-Capacity-Type-I-Duty-Rating-368/100659876?N=5yc1vZaq3dZ12l2
Just my thinking out loud. I definitely don't use mine all that often, so others that do can probably give much better advice.