What would be the best approach to installing an exterior beam to reinforce a load bearing opening?

I am taking out a good portion of my kitchen wall (18 feet) to allow flow into my living room. This is a load bearing wall, it was once the exterior wall, I will have a supporting column in the center of this opening. My ceiling height is low in my kitchen so I have to watch how wide of a beam I use at the p through. I can't put reinforcing beams in the attic because of the cluttered structure configuration, so I am adding a support beam on the living room side over the opening. This beam will be attached directly to the vertical roof supports and to the new reinforcing beams on each side of the column. This beam will be exposed and trimmed out to match the decor. What would be the best material for this beam and are there any new products out that are dedicated to this application?