I think my favoured option would be a bit like the Total War games.

You click once and it only plots the movement tracks so you can see how many turns it would take to reach places.

Only when you double click does the ship move.

Edit: I just checked Shogun 2 and the way it works is if you right click instead of left click, the movement track appears and you can move around as it updates so you can see just exactly where you can go in how many turns. Once you release, the unit moves, or if you left click it cancels.

Pretty good system Imho.