I think there are two or three markets with some overlap of requirements: transients, long-term slipholders, and liveaboards (if those/we are in the plan).
Clean heads and showers are a must. If there are broken tiles or gobs of poorly applied caulk then keeping things clean will be hard - maintenance and repair
of the bathrooms has to be a priority. I really like the two-compartment facilities where there is a dry, private place to towel off and get dressed. Give me a bench and number of hooks. The dry part needs a separate floor drain and better yet a floor grid so I'm not walking through the previous person's puddles in my dry socks.
Similarly clean laundry facilities.
Wifi. For real, with lots of bars.
I need local information. Transportation in and out, one-way rental cars, nearest airport, groceries, chandlery, auto parts, hardware, and restaurants. A map would be good.
A "Welcome" paper with a map of the marina on one side and contact numbers for service offered directly by the marina on the other side - oh and hours of service also.
Two 30s and a 50 for every slip.
Full length finger on at least one side of the slip.
Dock carts (clean also)
I've given up on dockhands and won't through a line
to anyone ashore until I have the boat where I want it.
Good attitude and helpful staff will go a long way to make up for shortfalls from perfection.