Flights, trains or boats to foreign countries for holidays longer than 5 days are partially reimburseable via CEA, see:
http://2012.acasducea.org/participation_acas.php or mail: catherine.doucet@cea.fr at ACAS (a sort of CEA holiday association). CEA employees can benefit of up to 3 such reimbursements per year - see BLG office in building 608 on the main CEA center (open for visits without an appointment every day of the week between 9:00 and 12:00; for the first visit you need to show your CEA badge, your contract and your last tax refund; after that, all you will need are the tickets and boarding passes used during the trip you are trying to get reimbursed for).