Sorry, no new text here, just a pointer to Drupal Mystery #1: Teasers. From my comment on that page, I'd like to see teasers set up with three radio button choices that the user must select from, per below. (And all build into core, of course.)

( ) Set teaser to <input some number> characters. (If left blank, Drupal will use the "Length of trimmed posts:" setting, under Post settings.)