The closest is the Key Largo casino at LaCabana (next door to AM). Its very very small but we like it as we go to LaCabana and its only steps from our back door. And yes its walking distance. Obviously you can jump on the bus and be to any of the other ones within 15 minutes (Alhambra by the Bucuti or down to Palm Beach where there are casinos in each hotel) Even a bus ride into "town" to go to Crystal Casino or Seaport Casino will only take 1/2 hour or less depending on how many places it stops!