This is important. My dad used aromatic cedar 50 years ago to finish the attic. Aromatic cedar cannot be finished. It contains natural oils that prevent finishes from curing. If it already has a protective coating you should be ok. Bare wood? Sand an area and sniff.
I agree wholeheartedly with Jim for two reasons. One - its a beautiful wood. Why gild a lily? Two - why make something that is almost maintenance free into a maintenance item? As is - you'll never have to do anything to the cedar. Paint it, and you'll be painting again inside of 10 years.