The Paris Visite card let you travel on metro, RER (Ratp and Sncf), buses, Orlyval and Montmartre's Funicular for the number of cosecutive days and the zones you chose.
1-3 zones cover the city centre and the first outskirts, they're good for touristic aim.
The cards that cover zones 1-5 include Roissy-Charles-De-Gaulle and Orly airports, Versailles and Disneyland.
You will also have more than 100€ discount on:
Arc de Triomphe -20%. Espace Dali -5.50€. Conciergerie -20%. Musée de l'Armée -20%. Chateau de Fontainbleau -2€. Musée Picasso -2€. Provins -4€. Cité des Sciences et de l'Industrie -25%. Musée Grevin -30%. Galeries Lafayette -10%+gift.