Cedar works as a trim and will accept polyurethane finishes. With the finish material in place, the cedar aquires a deeper red color and the grains are richer. You will not need stain.
I lived for 11 years in a house trimmed in nothing but cedar with some oak accents and recently sold it for $375k. It can be a very good looking wood and will meet your needs, particularly if your home's architecture dictates something other than traditional colonial hardwood.