Going to PME school in residence=big plus, generally. Expeditionary Warfare School (captains), not so much (do it by seminar/correspondence); but resident C&S (majors) or War College (LtCol) are very good for your career.
What's generally bad is going to Naval Postgrad or a civilian institution full-time on the military's dime. They WILL make you do a payback tour in a billet making use of that field. That's doable for ground siders, but for a pilot, 2 yrs out of the cockpit for school and 3 in a payback is generally a kiss of death in the Corps. You may be recognized as the best operations analyst/statistics weenie in the Corps, but you'll likely retire a major. If you like that, awesome, just know it when you sign up.