Weekend in Paris Itinerary:

Transportation
I took the SNCF overnight fast train from Antibes to Paris for about 40 euros (with Carte 12-25 discount), including a bunk in a 4-berth. For my return trip I took an EasyJet flight from Charles De Gaulle airport to Nice and the bus from Nice to Antibes. While in Paris we took the metro and walked everywhere.
SNCF website: http://www.voyages-sncf.com/
EasyJet website: http://www.easyjet.com/

Lodging
We stayed at Auberge Internationale des Jeunes near Place de la Bastille. The location was great and the neighborhood was nice, but this place was completely bare bones. Each room had some bunk beds and a sink, but the toilets were down the hall and just stall style, not a separate washroom with stalls inside the room, so basically if you had to pee and someone was walking down the hall they could hear you. The floor didn't have enough showers for everyone and the washroom with showers was co-ed with sopping wet floors. This made washing and dressing very difficult and time consuming. Also, the place was literally packed with high school kids, possibly on a school trip, intermingled with backpackers. Bottom line: it was cheap but I wouldn't stay there again.
website: http://aijparis.com/

Food
We didn't make any plans for food, but ate pizza at a little Italian place in Place de la Bastille, grabbed pastries, had lunch at a patisserie in the Latin Quarter (quiche, crepe and a soda for 7 euros? Amazing!) and snacks from Monoprix. We also had breakfast provided at the hostel, though it was pretty disappointing (a hard mini-baguette with jam and tea).

Activities
We mostly spent our time wandering around, taking pictures, and enjoying the city. We also went to the Musée d'Orsay and attended mass at Notre Dame and a short, free choral concert at a church near the Champs Elysees. Unless you have a checklist of things you MUST see or do while in Paris, I highly recommend this method of visiting the city. It's relaxed and gives you a real sense of the place rather than the typical tourist experience. Best of all, almost everything we did was free.