Many storage facilities offer those exterior units only, the ones with metal doors that roll up. But others offer multiple-story buildings with stairs, elevators, and different access points. Choosing may seem easy at first, but in order to find the best unit location for your needs, you must take into account the approximate weight of your belongings and how often you'll need to access them.
Frequent Access or Lots of Stuff
If you have a lot of stuff or plan to make frequent visits to the units, you want either a ground floor unit or one that you can get to by elevator. While upper floors will also be accessible by stairs, you don't want to have to drag boxes up and down stairs all the time. The elevators make loading and unloading the units really easy, especially if you're constantly moving things in and out and using a hand cart or dolly.
Lighter Goods and Less-Than-Occasional Visits
Some facilities have upper floors that are accessed by stairs only. These units are good for lighter items that are easier to carry upstairs, especially if you don't plan to move items in and out of the units frequently. If you need to store general household goods while you travel overseas for a few months, for example, this is a good type of unit to have. Because they are accessed by stairs, you may be able to find lower prices on these units than on those accessed by elevators.
Really Heavy Things
Really heavy items need to go on the first or ground floor of the storage facility. This is especially true if you're storing multiple items, like several large couches and pianos. Not only will that protect the other floors from the strain of the weight of the items, but you won't have to deal with wrangling the items up or down stairs, or through elevator doors. You may also want to use the exterior-access drive-up units instead of wrestling with heavy items along a hallway, though keep in mind those exterior units likely won't have climate control options, even if the rest of the facility does.
You'll find different unit types at each self storage facility, with some places offering maybe a couple of types, but others offering several floors and variations. Once you find the right type of unit and find the size you need, you'll be able to store your belongings easily.