I wouldn't consider myself a trail rider per say...but for spending long hours in the saddle I do ride the wade style that cowboybob posted a picture of. I have no preference as to square or rounded skirts, I base that on the conformation of the horse. I haven't noticed much difference in weight really. One thing I do like about Renee's saddle is the narrower fenders! I dislike the big wide ones. Wide fenders are cumbersome in my opinion. If I am going to spulge on cumbersome parts it would be the stirrups. I could dang near promise if you ride all day in a nice set of at least 4", I like the 5" but have 6" monel/brass bound wood stirrups(with or without blocks) you would throw those skinny tin stirrups in the trash. Also with cowboybob, and like smrobs saddle, I do not like a padded seat. I have had my ass rubbed raw more by padded seats than not.
I would consider different rigging styles and placement for fitting different horse conformations. Also strings are handy for attaching necessities. And if the saddle has horn a proper rope strap.