One thing that would be rather nice to see is an increased chance that a staff officer gains skill in the job they are doing. This would make the position somewhat more useful, and also allow you to use the to make otherwise not so valuable officers at least somewhat more valuable. I would suggest a something like (15-Current_skill) is added to the chance that the officer gains experience if their skill is <15. Or a straightforward gain of 5% per year so long as the skill is <15%.
It would also be interesting to have a staff and command college/school which you could build and then send officers to that would give chances to gain additional skills. Staff college would give them a chance to gain: operations, logistics, etc skills while Command college would give chances to improve initiative, training, and operations skill.
I would tied the schools to rank so you need R3 to go to the schools and you could only attend once. Attending the school would also take 1 year.
It would also be interesting if you could appoint officers of R3 and up to teach at the regular academy. This would give an increased chance that their skills are boosted for graduates. The degree of the boost depending both on the skill in question and on the officers skill. For example a officer teaching at the academy with a training over 100 would give a chance of 10% that a graduate starts with the ship training skill +25. While an instructor with logistics 10% would have a chance of 25% of adding logistics at +5% to any graduate. This might be too unbalanced though and possibly not really necessary.