The most fun action to do, and the one that tolerates the most micromanagement, is moving fleets around to make them do something useful.
Building ships and fleets is a clearly preliminary task that should be simplified and stripped down to leave only the interesting decisions, such as what shipyards are most suitable, what ships models and improvements should be researched and produced, which assignments need new ships more urgently, etc.
Even using fleets could be boring; the player should be allowed to automate tasks such as patrol routes/zones, escorts of civilian convoys (possibly including escorting new military ships to their assigned fleet's home if travel is dangerous), generic travel, exploration with long range sensors, and so on.
There might be some opportunities to turn boring abstract actions into regular fleet movement (for example, explicit temporary fleets representing convoys of reinforcements or cargo ships instead of abstract movement of resources)
Regarding moving all units every turn, player attention to each fleet should be required every now and then (e.g. when a multi-turn order is finished) but optional every turn, with some appropriate user interface to efficiently exclude uninteresting fleets that should continue following the same orders.
For example, if the enemy Death Star is detected, the right turn to inspect all fleets, decide which ones should take part in a great offensive against it, and changing their orders to execute the new strategy is right now, regardless of feelings about micromanagement. The player would simply enjoy a special, important "big turn".