What is the best way to handle accounts with multiple locations/offices?
But it really would depend on how the locations are split up and how your org is setup, are they different buying centers? do they belong to different sale people? What is your security like?
If they are different buying centers or they blong to different sales people I would create the account (using a naming convention) and relate it to a parent if needed.
If they aren't different buying centers you can still create them as an account a use the site field or create a custom field to capture the location.
Fore example Global HQ > North America HQ > Regional Office > State / City office
For retailers it can get challenging as you might have the company > division > region > district > store. In this instance the store may be an Account, but if the region or district does not have a physical address but is just a reporting territory, then use custom fields on the Account to denote how the store "rolls up."
More on what should be an account: http://www.shellblack.com/salesforce/sales-cloud/accounts-and-contacts/