OK, here's one that always bugs me when I see pics of pads (my own included). I'd want the plumbers to spend just a couple of extra minutes and $3 worth of PVC to plot all the components in such a way that they could someday be replaced. For example, instead of jamming all the suction and return manifold valves right up next to each other, leave enough space between them to cut them out and put a new one in, by using couplers or whatever. Same goes for everything: the SWG unions, pump unions, check valves, whatever. In other words, have them think in terms of the next time, not just this time. This notion would have to be communicated before they run the first pipe in the ditch, because it's how they come up out of the ground that usually drives the worst of this bad-practice.
I guess it's too late for a drain on the pad. I have one, and it comes in very handy when I have to drain the filter.
Lights over the pad, of course. Surveillance cam over it, too, to keep an eye on things while away. Ethernet cable at the pad, for future automation?
Hose bib near the pad?
Soft water spigot to fill the pool? I have high CH fill water, so that's my obsession. Maybe not in your area?
More later...