I will be in Venice prior to leaving on a Viking cruise. Wondering if things like water transportation and tours are best paid by cash or credit card. Is tipping standard and if so at what amount?
Credit card will be your primary form of payment. Vaporetto require a ticket or pass purchased before boarding. Tours - book online in advance with credit card.
Read Rick's advice on tipping: https://www.ricksteves.com/travel-tips/money/tipping-in-europe
Tipping is not normally a thing among Italians, but you can bet about every place in Venice will angle for a tip, mentioning it, noting on the check that "Service is not included" (In English on an otherwise all Italian language check), but feel free to either not tip, or seek to round up the bill a couple euro or so.
If you do want to tip in restaurants, you will often be told the tip cannot be added to the bill if you're paying by credit card. That means you'll sometimes be able to tip only in cash.