So, the LEAD platoon commander job is still around... I was one of the first to do it in 1997 (holy crap how old am I now??).
Here's my 2 cents....
Don't buy into the notions of getting "observed time" and how good it will look on a fitrep. Do it if you want to be around young Marines, getting paid to PT and teach some basic courses. You won't have another opportunity to influence young Marines for years, and that's assuming you get to a squadron and get a maintenance job to start.
If you are looking for the best thing to do (career wise) while sitting around doing basically nothing with your time, I will have to recommend doing EWS. Get the jump on that--you will never have more time on your hands in your career than when you are waiting in Pcola or waiting between pipelines. If you think you can knock out PME during advanced or once you get to the fleet, you will be shocked when you discover how wrong this idea is.
There is nothing wrong with the other mindset either--enjoy your time while you can. While I was doing the LEAD platoon commander thing, most of my buddies were doing absolutely nothing but dodging any responsibility on any kind while sitting in the pool. Just keep yourself out of trouble, be where you are supposed to be, and get ready for a very challenging pipeline whereever you end up. Bacon