How can I increase high wealth tourism?

This is based on my own experince.

I myself made sure to have several other citys in the region. A few of these cities are based on High-wealth population.

In these cities, I then made sure to have the same means of transportation I have in the city that is based on tourism. Having my "High-wealth" cities reaching a population of >100.000, gave my a significant boost to tourism. (not saying that 100.000 pop. is the key)

My Casinos and Landmarks are running like a well oiled engine. Making it possible to lower taxes for the general pop. = increasing happiness!

The Masstransit that I use: - Airport - Trains - Busses (regional) All of these are placed in all of my cities!