Given the trim on your windows, ceiling and base, I'd suggest a Colonial style wood mantel, finished to match the rest of the trim. A blank wall, with a fireplace opening, shown in your first photo, is a much more modern approach, while your house appears to have strong period character (I can't tell which architectural period). The dark, contrasting material and simple, rectangular shape in the location for a mantel, in your second photo, is also very modern and inconsistent with the rest of the room. Here's an idea of what you might do, less the paneling:

First, you might want to have the chimney cleaned and inspected. Second, I'd make an effort to contact the former owners, ask their advice: how often and how hot did they burn it, was is used after the pine trim was added, any issues you should be aware of before you fire it up... Then, you could build a nice hot fire [I know, not really the time of year for it], and monitor the temps in the areas you wish to change. Of you could just change it out as you please, and plan on never burning anything hotter than a candle in there...

I saw mantel unfinished "kits" at my local lumberyard. Worth checking to avoid shipping. Had both the mantel and the surround, ready to stain and assemble. Near that display was wood trim with photos for how to customize your mantel. I don't know where you live: It was a Menard's store. A mantel is really (usually) a long hollow box. It can really be made out of any kind of wood, then various moldings added. If you have some rudimentary woodwording skils (like mitreing) you could easily dress up a plain one with moldings.

Amber, with all the business already going on w/the fireplace, are you sure you want more things around it? just what I see, your mantel surround, (the 3-sided white piece) is too small. proportionally, it's just not right. (to see what I mean, look at this pic. very similar FP. ignore the decor. just look at how the surround properly fits the stone tile work) your mantel is more of a traditional looking piece that belongs to another type of FP. And the little mantel items look like miniatures sitting under the tv. I don't mind a tv above the fp (others despise it) but what is going on w/the gray/white accenting? you have what appears to be a travertine type stone in very warm pinks/browns, and then a blue/gray accent paint color above, mixed in w/more gray on the wall. I think this is the look you want? rather that break up the height w/color, use the white all the way, w/the trim work. and notice how the surround fits the FP, along w/the full mantel. this type of surround would look better on yours. you have a gorgeous tall ceiling and I assume some windows, and this small fireplace. I just think with what you have, it can be reworked a little better. here are a few photos to show you what I mean. take a look, and if you don't like them, you can tell me to pound. these are similar set-ups to your room this is similar to your trim work,,it's just spread out a bit. it's blurry,,,but notice the surround and proportion to everything around the FP.