Ok, before either one of you go out and get the things I mention, I would suggest also checking a few other opinions as well. Everything I'm naming off is just me doing calculations in my head of what I think would do well for your systems.
For a 55 gallon:
40-60 hermits, same type recommendation as Asbury's
20 Mexican turbo's
40-60 nassarius snails
20 ceriths
1 fighting conch, maybe two but I'm not sure if they get along in pairs
Jawfish
3-5 cleaner shrimp
2-3 emerald crabs
Both of yall could probably bump up the number of cleaner shrimp, these include peppermints, and scarlet cleaners plus some other species.
I would also recommend that both of you look into purchasing a detrivore kit. This will come with many creatures that are beneficial to your sand beds. However look through it first, because some of these kits some with sand SIFTING creatures instead of SHIFTING creatures. When you buy a sifting creature it is sifting trying to find food, which just happens to be the little additional creatures that come with your detrivore kit.