If you can't change your plane ticket to take advantage of the sleeper train from Zurich to Venice, then visit www.adp.fr, the Paris airports site, to see all your choices for getting into the city and for transfers between airports. The site is viewable in English. Unless the hostel you choose is close by the end of one of the Air France coach or Roissybus routes, your most flexible option would be to take the RER B Line from CDG into the city and then take the Metro to the station closest to your hostel.

About the Zurich to Venice, I looked on raileurope.com and only see these departure time:

From Zurich to Venice direct
09:07 17:06 Venice 355-IC Daily

From Zurich to Venice via Milan
07:42 11:40 Milan 153-CIS Monday-Saturday
12:05 15:09 Venice 615-IC Monday-Saturday
11:09 15:35 Milan 383-IC Daily
16:05 19:09 Venice 625-IC Daily
13:09 16:45 Milan 155-CIS Daily
17:05 20:09 Venice 629-IC Daily
15:09 19:35 Milan 387-IC Except Saturday
20:05 23:09 Venice 639-IC Except Saturday


I didn't see any that leaves at 23:09?

rkkwan, Is there something I am not seeing or place I haven't looked?

Thanks

It means that raileurope.com doesn't sell tickets on that train. I am not sure if you can book it online via the Swiss Federal Railway's site: www.sbb.ch, but perhaps others can help you with that.

But that direct daily overnight train EN303 certainly exists on all major railway's online timetables.

I just visited the Swiss Railway site, found the night train in question, and discovered I could have proceeded to buy a ticket online.