Since you like to learn I would strongly encourage you to take Science of Diving when you are qualified to do so. It is a requirement of SSI Dive Guide and you have a few levels to complete prior to begin eligable but it is a very good course. I would also put Stress and Rescue high on the list as well. But for your advanced open water - get your 25 dives in and most SSI shops will package something like Deep, Boat, Night and Buoyancy.
One question though - how did you get Navigation before completeing OWC? Normally, you have a couple of dives associated with that certification.