My little black TWH (the one in my avatar pic) is the first TWH I ever rode - I was just horse-shopping for a good trail horse, knew next to nothing about the breed or gaits but wanted something with a good and willing temperament. We did a "test ride" in the arena and out on a short ride around the perimeter of the farm.
I tried to "play it cool" and not seem too eager, since I didn't have a trailer with me to take him home that day. . .but I was barely out of the seller's driveway when I called my parents to tell them "I just found my new horse." That was just over ten years ago. . .my lil' blackie is now 13 years old and I plan on being his "forever home." He's just awesome.
My boyfriend has a sorrel gelding, which I usually ride when we go on camping trips because he's a little bigger and faster and able to keep up with my boyfriend's long-legged 17hh TWH.
I remember one ride in particular, though, where I was out front and moved the sorrel up a couple of gears. The trail was hilly, with lots of twists and turns, but that horse never missed a stride and was smooth as glass the whole time. There was no tension in his movement, though - he was totally relaxed, just really moving out.
I finally "shut him down" when I realized that the rest of the group was back in a cloud of dust.
When they finally caught up with me, my boyfriend asked if I realized how fast we were going. It's just one of those things that you can't explain it until you've felt it. They're amazing horses.