This table shows the total annual cost for 3 Season Passes at Six Flags America (Maryland, Baltimore - D.C.) with the Premium Dining plan against 3 memberships with Premium Dining during the Halloween sale (September / October 2020).
This page compares the Six Flags Halloween Sale 2020 costs for passes vs. memberships for 3 people. For a different number of people (1, 2, 4, etc.) see this page.
Season pass is a much better value, saving anywhere from $65 to $380 over the year, depending upon the Membership level chosen.
See more notes, details and tips on this page.
Costs below do not include taxes. And Six Flags will probably slap on a "handling" or "convenience" charge when you go to check out, but those won't affect the analysis of which option is a better value as they apply across the board.