The Carriage Ride at POR is $30 (and we tipped, though the driver did not want to accept it), and I guess it's similar at FW or WL. Don't know about horse ride, except you have to be 9 and wear closed toe shoes.
I looked at the price last week when we were there, but I don't recall exactly. I *think* it was $16 for 30 minutes for the 2 person one and the larger ones were $18 per half hour.