What would be the most efficient way to get from Split to Venice. The train seems to have to go to Dobova, Ljubjana and then Venice. Or is the bus to Trieste and then the train to Venice, the best way to go and how many travelling hours would the bus take? I am planning on buying a Eurail Pass

If you're thinking of buying a Eurail pass to visit Croatia and Italy, don't - it'll probably be a lot cheaper to buy tickets as you go.
From Split to Venezia, either take a bus to Trieste (perhaps 10 hours) or Jadrolinija's overnight ship (www.jadrlinija.hr) to Rijeka then a bus to Trieste, then a train, or an overnight ship to Ancona (www.bli-ferry.com or www.jadrolinija.hr) then trains.

Jadrolinija's address should be www.jadrolinija.hr.

Thanks GeoffHamer,
I've checked both sites and either could work. We will be travelling to Florence, Cinque Terre, Paris and then Amsterdam, which is the reason for the Eurail Pass. 3 countries for 5 days. Would you still think it better to travel the ways you've suggested? I'm just not sure how well all the trains connect with each other. Is the bus ride up to Triete scenic?

Go with the bus, the scenery is magic

It depends how long you want to spend on a bus. The scenery along the Croatian coast is superb, but I couldn't take a whole day sitting on a bus. If you spread the journey over a couple of days, it could be very enjoyable.
The journey via Ancona would be quick because you'd sleep on the ship, then have a quick train journey, but there'd be no scenery.

Geoff
If you were to spread the bus ride over a few days, where would you stop for the first night?