I'm trying to figure out the number of users on my site that visit the site more than once in a given period using Google Analytics.
Can someone help me with what the best method or report is to get this value?
You are looking for the "Frequency & Recency" report. You can find it under Audience -> Behavior -> Frequency & Recency.
For the selected time range, it tells you how many sessions are from users that visited exactly once, exactly twice, exactly thrice, etc. The report is limited in so far as it doesn't have the number of users associated with the session counts.
If you want to know how many visited more than once, you can subtract the number of single visit sessions from the number of users found on Audience -> Overview.