For the third year in a row, Miami-based Leon Medical Centers Health Plans made a huge marketing push during the Super Bowl—rubbing elbows with the nation's advertising biggies. For viewers, the seamless transition between commercials made it seem that Leon was a nationwide marketer, but in fact it was purchasing local spots at much less than the $3 million for 30 seconds that the big boys were paying. ''It gets that buzz going,'' said Leon spokesman Rebecca Larger. ''It gets the phones ringing. It does not necessarily reach our demographic''—senior citizens on Medicare—''but it definitely targets the children, the sandwich generation, the decision-makers for the seniors'' about which Medicare health-maintenance organization is right for their parents.