Hey Erin,
For a generic report of all campaigns run in a given time period, you can use the "Campaign Activity" report type, and specify a time frame. This will provide a list of all campaigns run in that time period, as well as some information about the number of leads that each one processed. You can also use "Email Performance" for any emails sent during a time period, or "Campaign Email Performance" for Email sends grouped by the campaigns from which they were sent.