There is a lot that can be done with an existing fireplace to bring to a status of more appealing and use of space.
Start with just updating the fireplace doors, simple natural steel or black the possibilities are endless in décor and accessories that can enhance the appearance. Go further into replacing the log set if gas and or interior panels of the fireplace box.
If you are looking to add a hearth and the current fireplace is on the floor, raising the fireplace box will most likely be needed. This will have to have the existing flue cut which means the entire space to be opened and exposed. If you are at that stage might be best to go ahead and update the firebox and replace to a larger or even if to gas from wood.
Converting a wood fireplace to gas can have some challenges to overcome. Gas line current in space? How far and of what obstacles to run gas line? Flue may have to be lined with a b vent style flue. What are area building code requirements and of existing flue material fabrication.
Replacing or adding a mantle should be considered with new façade of fireplace. Have the structure prepared to bear the weight if of large wood timber.
Installing a TV over the fireplace is of a great focal piece for the room. Add an articulating recessed TV mount in the wall. This will give the TV a look as of a piece of art work on the wall, and have the ability to pull away and be visible for an adjacent space. Have all components for the TV to include audio video recessed in a cabinet or cubby of the fireplace with matching wood work of the existing room décor. This will give you all the control for TV to add the go pro video, IPhone/Apple TV, or the Sonos equipment, in an appealing space.