Just got back top the USA, wish I was still over in Europe!
Anyway, we ended up using the ES from Rome to Venice and it took about 4 hours. It was pretty expensive ($212) since we booked a "flexi" ticket and first-class. (In actuality, I think it may have been cheaper top fly Ryan Air (122 EUR), but the flight times where not convenient with our limited time.)
We also used the IC Plus from Civitavecchia to Rome (Termini) and this cost $27.
The only "incident" we had was with a woman who acted like she worked for the train station, helped us get our luggage on the train and find our seats. Then insisted on a tip and was upset when I chose the lower amount between all that I had on me of 1 Euro or 20 Euros.
Thanks all for the help and I hope this info helps someone else!