Sheepskin butt pad. I've used one for years on different bikes. I'm also tall, 6'4". Some come with a valasic foam in it. That's what you want. Boosts you up an inch, which makes a big difference. You can also move the pad around if you buy a large one.
That way it puts pressure on different parts of you butt to give you a break. I don't leave home without it.