Buses are the best kept secret in Paris. For only the price of a ticket, you could be riding in front of the most beautiful monuments, discovering neighborhoods, getting a feel for distances between places you'd like to go back to and visit.
Take for exemple the bus number 69: it starts by the Eiffel Tower in the Champs de Mars, near avenue de la Bourdannais and rue St Dominique. Then, rue de Grenelle, you'll see l'Ecole Militaire and les Invalides.
Down the way, you'll pass the Orsay Museum, l'Institue de France, St Germain des Près, le Louvre, le Palais Royal, la Conciergerie, l'Hotel de Ville, Notre Dame, le Marais and le Père Lachaise.
Taking the bus is also a great way to chat in French (look for older folks, they are usually happy to chat in the bus)...
Note: avoid rush hours: 8 to 9:30 AM and 5 to 6:30 PM or the ride might not be that enjoyable. Always check your bus schedule: number 69 does not run on Sundays nor holidays... For more info got to the RATP website
To know all about public transportation in Paris + special tips from my own experience, consult my lesson here.
If you too know of a great bus ride, please share it with us and post about it in the comment section!
Born and raised in Paris, I have been teaching today's French to adults for 19 years in the US, France, and to people around the world over the phone and by Skype . My method is proven and unique, and, based on my students' goals and needs, I've developed high quality audiobooks and audio lessons for all levels. Good luck with your studies and remember, repetition is the key!