I will be in Arabba from 2/28/15 to 3/7/15 and would like to take a day to do some sightseeing in Venice. What is the easiest way to get around without having to rent a car?
The best, and easiest, way into Venice IMHO is via train to Venezia Santa Lucia station. Arabba however doesn't have a train station. There are several ways to get to the train stations in the neighbouring cities, spanning various price ranges.
Bottom line is, logistics to/from these ski resorts are everything but easy.
Taxi it to Bolzano
You could get a taxi to the closest important stations, which are:
- Stazione di Belluno km 70 - Stazione di Brunico km 50 - Stazione di Bolzano km 75
Considering the distances, this could turn out to be fairly expensive. Moreover, there are no direct trains from, say Bolzano, to Venice. The connections run though Verona.
Bus it to Belluno
There is a bus from Arabba to Belluno, whose timetable you can find here (thanks to @ptityeti). From Belluno there are several train connections to Venice, which pass through either Castelfranco Veneto or Conegliano.
Dolomiti Ski Shuttle
Another option is the Dolomiti Ski Shuttle, which runs from Arabba to Venezia Mestre station, from which you can get a train into Venice. This would be the easiest option, however the shuttle runs only on weekends so you will have only two options to visit Venice: either fro, 28th February to 1st March, or on the 7th of March (which is your departure date).
A tentative shuttle booking from Arabba to Venezia Mestre for the following dates:
- Arrival trip: 28 February 2015 departure time 06:15
- Departure trip: 1 March 2015 departure time 17:00
Yields a cost per person of 45