I'd like it if a small destination marker would appear at your fleet's next immediate destination.
That has two reasons:
1: The following scenario has happen to me far too often: I'm on course to somewhere, than something makes me deviate from the course, let's say a hyperstorm. Now I click and hold somewhere off int he distance to avoid it, draw the cursor around the obstacle while my fleet follows, and let go of the button when the danger is circumvented. My fleet is happily back on course and... but wait, it suddenly stops in the middle of nowhere. Oops, I forgot that I didn't just evade, but set a new course to some random point in space. Hopefully no enemy is in pursuit...
2: Another scenario:
Ah, so that is the system we have been astrogating to, let's see, where best to enter... wait, what, we just passed over the star? Ohh, it's the next system over, and this one just happened to be on the same vector....