Make sure that your tub is actually appropriate for this application -- usually drop-in tubs end up having a ledge around them (before the walls) that collects crud and water and creates problems.

Otherwise, keep the number of tile types simple. Match either floor or shower -- I'd match the shower and then maybe use the floor tile in a niche.

S drop in tub is not the correct choice for an alcove installation. You need an alcove tub with the integral tile flanges.

While that tub has the required tile flange, it's an off brand import that I would not recommend using. Cast iron would be superior for heat holding over acrylic. But if you choose to go acrylic, pick a good name brand like Kohler or American Standard.

For design, I prefer color blocking for a modern look. The tub being white, should be nothing but white. The floor should be nothing but dark slate. The walls could be a fun accent color and work with modern. No wood aprons if this is to be a tub shower. It will be damaged quickly.

What about the floor, apron and back wall in a darker tile and the sides in a lighter (same scale) tile?

I understand this is an old thread but wondered if anyone knew what exactly one needs to look for in terms of making tile or quartz have a flush apron?