Tile Size, Retina vs. Retina, iPad vs. iPhone

Kind of a funny question. I hope this creates a lot of good thinking.

I am involved in the development, early alpha phase of my current orthogonal game project. I am experimenting with different tile sizes. A few questions, since I would like to leave on my right foot.

• Should I distinguish between tile sizes (80x80, 32x32, etc.) on the retina and non-mesh displays, does the iPhone vs. iPad display?

• What is a good recommended tile size that suits both the designer and the artist ... and why?

Purpose:

• I would like to have clean, clear visual effects regardless of the display format. Cartoony, colorful images from 16 to 32 bits regardless of display.

• I would like to save a texture size of 1024x1024 for my atlas. I hope this gives me enough tiles to make the world look good and not crush my map system.

• My current map size is 200 tiles wide x 120 tiles high. The map will be a small detail (sea-oriented) of the Mercator projection of the Earth.

Thanks in advance for all the helpful tips.

E