Backup database and clean old backup question
You should probably move from maintenance plans to SQL Agent Jobs and leverage a script like those written by http://ola.hallengren.com/.  You would create a Job Step for each database.  It will give you the flexibility that you are looking for. 

UPDATE: My info above was incorrect. You can use the Ola.Hallengren.com script to do what you are looking for without having to add a job step for each database.  After reviewing the script info I saw this: 

From: http://ola.hallengren.com/sql-server-backup.html


  CleanupTime
  
  Specify the time, in hours, after which the backup files are deleted.
  If no time is specified, then no backup files are deleted.
  
  Backup files are deleted after each database is backed up and
  verified. Backup files are deleted only if the backup and verification
  of the database were successful.
  
  DatabaseBackup has a check to verify that transaction log backups that
  are newer than the most recent full or differential backup are not
  deleted. This is to guarantee that you can always perform a
  point-in-time restore.