What is the best and least expensive way to travel from Piazzale Roma to Santa Maria del Giglio in Venice?
Best? Vaporetto, 7 euro. Least expensive? Walk, 0.00 euro.
Liz, Venice is an island...you can't get too lost.
As was said already you certainly can take the vaporetto just a few stops (you would have to take the one that makes every stop, not the express). But the easiest way, and if mother nature is working with you regarding weather, is to walk. Venice is a very walkable city but be prepared to get lost, that is half the fun. To get to the church you just head out from the piazza in that general direction and you will get there. Should only take about 30 minutes or longer if you stop along the route. It is a lovely church. You will enjoy it.
Don't forget when using goggle and other mapping apps that they are computer programs which don't understand bridges and Venice crowds, to say nothing of the wow!! factor I might nearly double the estimate.
I don't understand the phrase "getting lost in Venice is half the fun". I was recently in Venice and got lost. It was not fun, it caused a lot of anxiety, and put a damper on my visit, especially since I was by myself. That said, my hotel was directly across from the church you mentioned. I managed to walk to the Piazelle Roma. It didn't take too long.