Finishing the basement can add allot of practicality and comfort. It can be configured to provide guest bed and bath, recreational activities for the family or a high tech entertainment theatre.
In the case of entertainment, consider having the contractor install outlets, video cable and speaker wire for surround systems. Even specialty lighting connected to a remote dimmer control.
Also consider the kind of furniture, like whether using a surround couch or bean bag chairs. The type of usage, furniture and other factors determines the shape and decor of the room. Also, be sure to address climate control and ducting issues to assure good air quality and circulation that prevents moisture and mold issues. Speaking of which, before you begin the basement project, be diligent from the start. Inspect and resolve moisture, leaks and duct or pipe condensation situations that may spoil your project after it's finished.
Remember that materials, textures and colors really make a difference when attempting to make the basement a cozy, relaxing environment. Don't forget to build a small containment room with good access as a utility room for the furnace, water tank and laundry, so as to create more privacy in the rest of the basement decor.