We need to get from Interlaken to Venice. I'm trying to avoid one-night stops, so I'm wondering what the fastest/best way to in one day is. Looks like the bahn.de site doesn't have updated information for those routes for August yet. One catch is that we may be attempting to do this on a Sunday. I don't mind making a day of rail travel if it's nice stops, etc. Has anyone taken a path they'd recommend?
Joel, you'll be just fine. You are looking too far out and the train schedules are not that reliable beyond 60 days.
CLICK HERE to see a current morning schedule for this journey. You won't be able to avoid the train changes. Note that the CIS train in the train category column is the "tilting" train (leans into the turns) and is a bit more expensive to ride. If you book later in the day, you'll be on less expensive IC trains. You can buy the ticket for this entire journey in the Interlaken Ost ticket office.
It's normally about a 7.0hr. journey although you can see the 13:29 run taking less than 6.0hrs.
We are taking the same trip in September. For your trip I entered Sunday June 15 into the DB web site and came up with an 8:01 departure from Interlaken Ost and it arrives at Venice Santa Lucia at 14:30. With two changes in the first hour and 10 minutes (in Spiez and Brig). Then it is the same train all the way to Venice. Only the last train needs a reservation. Making this is a 6 and a half hour trip.