If it is next to a room on the second floor( assuming there is one it is easy to access from that room. It depends some on the roof pitch over the garage. It can be done with attic trusses. It can also be accessed as you say from drop down stairs.

We have access from an adjoining bedroom on the second floor. We just used an insulated door to seal off the storage room above the garage. You would need a steep roof pitch and a second floor for this though. We went this route because I new we wouldn't use it to it's potential if it only had a pull down ladder.

Thanks! I should have mentioned that the house is a one story.

What about some sort of pully system so that you can load the large boxes on the garage floor and then "pully" it out of the way?

We have a one story. The attic space over the garage could be a bonus room if we finished it. We access the attic with a set of stairs at the back (inner) wall of the garage. Thae back wall has an entrance to the house, door to the understair closet, landing and then door to the stairs and door and closet for the water heater. It all lines up at the back of the garage so there isn't an awkward space. It is easy access to the attic.