Assuming you will have a non-aggressive reef and fish setup, here's my suggestion for you:
20 Cerith Snails
20 Nassarius Snails
5 Astrea Snails
10-15 Scarlett Hermit Crabs
2-3 Emerald Crabs
5 Peppermint Shrimp (You can also get a small # of Skunk Cleaner instead)
Maybe add a Fighting Conch, they do a great job at cleaning the sandbed.