designing for a electic fireplace insert

well, I am working on a basement room right now and I want to put a 39" Electric fireplace insert in.. I know it doesn't have the same requirements for clearances as our gas one upstairs, and of course not venting... but I want it to look as much like it was designed for gas as it can be... trying to get one of those really realistic looking ones

http://www.electricfireplacesdirect...lt-In-Classic-Flame-39-Dual-Voltage-Fireplace

that's pretty much what it looks like I know the site shows framing for the box around it, but what around the margin around the box, is there any standard for that? I want to make it look as normal as possible, not just a box in the wall... put a mantle around it,etc... ideas on how big of a mantel should be around it? sorry if I sound lost, I just don't know what is standard for making a fireplace look good