Originally Posted by
graraps
Tolbiac isn't that far from Orly...Having said that, I don't know why you'd want to fly OpenSkies, especially if you need to stay in Paris for a while and then return to the US...I highly doubt OpenSkies will still be flying this time next year...
Even if that were the case, the OP would in all probabilities be rerouted on BA, so hardly a major issue.
[edit]
aamilesslave beat me to it![/edit]
ORY is a little more "French" and a little less international than CDG. That said, it should still be straightforward. For Tolbiac, the easiest and cheapest route would involve taking the jetbus to the Villejuif Louis-Aragon subway station and then direct on the subway for 5 stations.
The bus leaves every 12 to 20 mins for Gate H from Orly Sud (gate E from Orly-Ouest) and takes about 15-20mins to make it to the metro. One way trip is €6.40. The odds are the driver may only speak French or bad English but that should not be an issue.
For cite universitaire, you have a choice of either Orlyval+RER or Orlybus to Denfert-Rochereau then RER to Cite universitaire (Orlybus might even have a stop bear cite universitaire but I am not sure). For St-Michel, pretty much the same except that from Denfert, you go in the other direction to the Luxembourg stop (or perhaps the St Michel one?)