I’ve stayed at Le Village Hostel, the breakfast was crappy but lodging was spotless and the people were friendly.
Have you been before? I would definitely want to walk all around and view art and architecture…Notre Dame,La Defense, the Pompidou, the Eiffel, Montmarte, the Louvre.
I guess the Marais district is now discovered but it is still fun.
One of my favorite places in any big city is the cemetery, and both Pere Lachaise and Montparnasse are fascinating explorations of Parisian history.

Don’t miss Musee D’orsay — it picks up with the “newer stuff” where the Louvre leaves off. It’s the biggest collection of Impressionist works and it’s not as crowded as the Louvre, so you might actually be able to see something. The building is the train station built for same the exhibition as the Eiffel tower. Invalides has Napoleon’s tomb and the attached armaments museum is uncrowded and interesting for an hour or so. Take the Montmarte funicular (covered by a ParisVista transit card) to the foot of Sacre Coeur for a great view of the city and you can wander back down through Montmarte. I also enjoyed the view from the Arch de Triumphe and the mini-museum inside. It’s a fair climb, but, IMO, worth it.

Three days is actually a little short for Paris — particularly if it includes Monday and Tuesday since many sights are closed one of those two days. While you can figure it out from any guide, the Rick Steves guides usually include a two page spread that tells you what’s closed and what’s especially crowded for each day of the week. I’d suggest trying to work in a 4th day so you can take a day trip to Versailles. I’d spend the first 1/2 day on the hop on/hop off bus tour to get the overview and get oriented. Your ticket will be good for 24 or 48 hours so you can go back to at least a few places and it will give you a chance to figure out which places you want to see and if the museum pass is worth it for you. On second thought, just buy a 3 day museum pass. It will save waiting in line, and you really don’t have enough time to wait in line.