Cowboy Boots: Good riding boots with a heel are essential for stirrup grip; try various styles to find the right fit. Even English riders might benefit from a pair; breaking them in before the trip is wise.
Riding Jeans: Opt for boot cut riding jeans like Wranglers, designed with seams on the outside for comfort during long rides.
Cowboy Hat: A wide-brimmed hat is a must for sun protection; consider one with a chin strap to avoid losing it on rides.
Vest: A warm fleece or vest is handy for chilly mornings, storing essentials like chapstick or a small phone/camera.
Warm Clothes and Pajamas: Layer up for cold mountain nights, especially in locations like Montana where temperatures can drop below freezing.
Sneakers / Hiking Boots / Flip Flops: Bring sneakers for ranch activities, hiking boots for nearby trails, and flip flops for warm relaxation days.
Shorts and Maybe a Bathing Suit: Pack shorts for warm days post-ride, and a bathing suit if the ranch has a pool or lake.
Long-Sleeved Shirts: Protect your arms from sun and branches with hiking or Western shirts, perfect for chilly rides.