If there are still some of you who are cardboard challenged and have yet to play Puerto Rico, there is a digital solution.
Many game designers use Excel to create simple game prototypes for testing. Tony Mitton took digital prototyping to the next level with his Puerto Rico Evolver, Puerto Rico AI on spreadsheets. I don't really understand, but he claims the AI evolves as you play. However, what I do understand is that the AI is strong and hard to beat.
Puerto Rico Evolver will only work if you enable Excel macros -- look under Tools > Macro > Security.