To get back to the OP and his question about what the next logical step might be. One answer was just plain more diving, but there may be other options if training is desired. The first thing I would suggest is to look at training for specialties that may help you in your diving. Just look at those specialties for what they are worth. If you find some you really like, and if you take enough to get a MSD certification, that might be a pleasant by-product.
You may also find that there are specialties taught near you that are not listed on the official PADI web site. These are called Distinctive Specialties, and they are created by individual instructors and sometimes by groups of instructors. They can be quite a bit more valuable than the typical specialty. A number of instructors around the world (not sure how many) are teaching a specialty in Dive Planning that is quite comprehensive and teaches a lot of valuable skills not found in the normal recreational program. One of the instructors active on this thread teaches a course called Intro To Tech, and he has a tech/rec workshop that is also very valuable. Believe it or not, several instructors in Florida offer a PADI Distinctive Specialty called Cave Diver, and it is the equivalent level of certification (and requiring the same level of training and skill) as a typical full cave diver course from a cave diving agency. Check around locally to see if something like those is being offered.
By the way, I am a MADI Master Scuba Diver Trainer who is a certified cave diver and a certified advanced trimix diver. I teach about a dozen specialties. I do not, however, qualify for the PADI Master Scuba Diver rating because I do not have 5 specialties myself.