I think the recommended packages from reef cleaners are more than you actually need. I would choose a package 1 or 2 tank sizes smaller than what yours actually is, you can even customize a package if you like. I like a combination of turbo, astreae, nerite, cerith and nassarius snails. The more diverse of a cleanup crew, the more things they'll be able to tackle. The turbo snails can get quite large and you're never sure what size you'll get if you're ordering online. They can easily knock off frags or small rocks that are not securely positioned.
I like to stay away from most hermit crabs as after a while they end up killing each other or other snails. I've left plenty of empty shells lying around the tank for when the hermits outgrow their existing shell yet they'll still choose to go after snails and steal theirs. Having extra shells help but if a hermit is set on a certain shell thats already occupied there's no stopping them. The hermits I do have now are scarlet hermit crabs which are a little more passive in nature than red leg/blue leg hermits. If you have enough snails, they'll take care of your cleaning anyway.