The best cities -- the ones at the top of the leaderboard -- spend design time combining the overall benefits of the various mass transit options into one cohesive mass transit network (MTN) that connects buses, streetcars, planes, trains, and ferries all together into one moneymaking machine.
Even if you have zero tourism, locating these nodes near each other will reduce traffic across your city and open up the local economy and earn you more money.
The MTN and Water
One of the philosophies I've found useful is to have my train station, ferry, and municipal airport all within walking distance of each other. Depending on the map, sometimes this can be unrealistic as getting rail over to the beach where your ferry is going to be may be expensive or take up huge amounts of otherwise valuable space. But on most maps, this is convenient.
The purpose for this is to create a single location where all tourists are going to congregate so that you can send your buses and street cars to that location, pick up the tourists, and then take them to another location specifically made for tourism -- a downtown commercial district. By thinking about tourists in terms of aggregating them, moving them, and disbursing their money, you can turn tourism into a system within your city and generate huge amounts of tax revenue with it.