Range

The ideal for a turn-based tactics game would be to set the units range (in tiles) such that for the majority (e.g. 75%) of units the user doesn't have to scroll the window to target attacks.

A typical screen size (pixels) is 1024 x 768; a typical tile size would be 32 (pixels). As such the 75th percentile range in tiles would be 24.

To maintain game accuracy, this would give tile size of tiles as follows: