What do I use to display multiple categories at a single point? Join or Relate? There are multiple building locations and each have multiple cost categories (electric, gas, trash, etc.). I have a point file for the buildings and I have a table with costs. Is this a one-to-many relationship (bldg.-to-costs)? How do I Join or Relate these? They also need to be labelled (I think this may be the critical point that decides which I use since it is difficult to label features with a Relate?)
For one-to-many, it would be a relationship class or a relate. For a comparison among Relationship Class, Relate and Join, see Deciding between relationship classes, relates, and joins—Help | ArcGIS for Desktop
There is no out-of-the-box functionality to label related table, but you could achieve it using Python.