I'm 5"7 and weigh 128 and I ride in a 16" seat. Anything smaller and I would not be comfortable. You shouldn't be crammed into a western saddle unless you are doing timed event where the seats are smaller and have a "pocket" to hold you in. I also like the butterfly close contact under the leg...both my training and show saddle have that. I also prefer a flatter seat as opposed to a saddle with a big rise in the front...that's wasted space IMO.
I agree with everyone that it really depends on the tree and use that will determine seat size. Some saddle shops will let you put a deposit on a saddle and test drive it. I think it takes a while to figure if I like a saddle or not rather than sitting in it for 30 seconds and making a decision. I have realized that I don't like a cantle with a lot of "dish" they seem to bite at the back of my thighs. When I order mine I order them with only. 5 inch dish. For me its those little things you don't realize until you ride in it all day! Posted via Mobile Device