ive ridden/worked with two clydesdales
daisy a 15.2 clyde x cob who i rode/looked after the only downside to daisy was although she was a perfect hight she was litteraly like a full sized clyde so it was like riding a 17hh+ but at a 15.2 hight meaning she was very wide and saddleing her could be a problem but she was a lovely ride and could really move when she wanted to and outrace alot of the other horses on the yard (although i didnt really try to stop her)
chester a 17.2 pure bred was a horse that i only rode in my riding lessons he was a nice ride but did struggle in the school as he was so big doing circles could cause him problems
but basicly ive found that clydes have loverly temperments and although very wide are quite a nice ride once you get used to them but you must remember they are a big horse and although they are more expensive to keep than say a 16hh because they eat a little more its not a massive amount more
also have you considered the idea of a clydesdale as a driveing horse daisy drives and goes very well in the carriage plus they can pull large amounts of weight