I love my Arista shirts. GORGEOUS. I am a collector of shirts and have probably every brand. Chestnut Bay tends to be a bit thicker and I love it in winter. Ariat has some pique that I have but I’m not crazy about them; their silky ones are superb, however. Tailored Sportsman are nice as well. Kerrits tend to be lighter and less fun in 50 degrees. I wear my shifts to work nearly every day under my coat. That’s how I justify having so many!! Enjoy!
I have occasionally bought the Kastels and feel like they are ‘special’.
OP, for your clinic, just a note that it would be nice to have a shirt or vest with color blocking. One clinician I had asked (for a summer clinic) for us to wear horizontal stripes as easier for her to see your posture/shoulders (I wore LLBean that day). I guess light shirt with darker vest would kind of accomplish that. to see if your shoulders are level or one is up/down, forward or back.
Enjoy and let us know how it goes.
Along these lines - I know you said you were planning on navy breeches, but there is something to be said for lighter colored breeches for both the ease of the clinician and if you’re planning on video - to review later. It’s amazing how much dark breeches can blend into a dark saddle sometimes. The clinics I have participated in have always been held in an indoor - but I would usually go with a tan breech and a darker top to stand out against the walls/kick boards. I spent not an insignificant amount of money on a couple of very good clinicians and wanted to be sure to get my money’s worth out of it both in person and the video to digest later.