Creating a group is a great idea. I'll do that for the new server that is being built. For this old server, this is a one time thing. I made this and it seems to almost do what I'm looking for.

EXEC sp_MSForEachDB 'IF ''[?]'' NOT IN (''master'', ''model'', ''msdb'', ''tempdb'')

exec sp_addrolemember ''db_owner'', [domain\login]'

Unfortunately it skips databases that don't have a check box by them.