I always want the top to start out easy and slow, not going too deep right away. Since I tend to mostly bottom for very well hung men, this means I don't want it balls deep for several minutes. The first few minutes not being too intense are critical for being able to have a long session. It's painful if a top just goes to town right away, and that's no fun.
After I've been warmed up, I like a medium-pace with increasing depth, eventually hitting as deep as they can go. Once they've been going at it for a while and I've really loosened up, then I do like more intense and sudden thrusts, but even this I want to be tempered with some slower moments. It's perfect when a top just knows when it's time to slow down for a bit, and then when it's time to intensify again. As you said, variety is key, but periods of a regular rhythm are also nice.
When I'm feeling really in need of a deep and hard picking, I like to lie on my back with the top on top of me, I take a big hit of poppers, and then I grab the top's butt and hips and I pull the top deep into me as they thrust. The feeling is super intense, but I think the fact that I am partly controlling it makes it more manageable. I do this with my boyfriend who is pretty much the same size as me though slightly thicker. He's skinny and I'm somewhat muscular, so I can really pound him into me hard, and wow it's incredible!
I also love getting on my knees in a "child's pose" (I know, sounds inappropriate, but if you do yoga, you know what I'm talking about) and have the top just go to town on my ass.
Ok, now I really need to get fucked...