Folks from other countries (funnily enough including France 
) are planning to take the trainhotel from Paris to Madrid to get to Debconf so lets join up with them.
Afaict the tickets are available 90 days or 3 months in advance so to get the cheapest fares we should be booking around the end of April.
Wed 22nd July 19:46 Paris Austerlitz
Thur 23rd July 09:10 Madrid Chamartin