Since the antlers are a neutral color, you might want to put some added color on your mantel. Some twigs mixed with some sprigs of dried wildflowers or berries that complement your room would be nice. Display them in a rustic container such as a fishing creole or old binocular case.
You could simply lay out some leaf garland and intermingle some twigs in a decorative manner. Then, display a row of colored candles in rustic holders.
Hunting antiques are fun items to display and add color. Examples are old shotgun shell boxes, books, binoculars, creoles, and calls.
I hope this at least spurs on an idea for you!