Position
Mostly, I only have a tickler's perspective on this. My wife always struggles to escape her ticklings regardless of position, but at the start, if she senses I'm putting her face down, she's a crazy woman. So I guess she finds it more torturous to be face down. The best part is, the closer I get to having her in position, the harder she laughs, even before I start tickling.
The whole thing is a process, and most of my life I derived intense pleasure out of the look on her face during prolonged ticklings. It has to be a quality almost beyond description to be the wife of a tickler that has a tickle fetish. Tickling her makes me feel like I'm twenty two years old again, and ready for action. The longer I tickle, the more desperate her reaction. The more desperate her reaction, the more ready for action I get, which just intensifies that delicious ache, which makes me find ways to turn the tickling up another notch. It's the tickling equivalent of a mirror image of a mirror which is another kind of hypnosis.
One way I have REALLY enjoyed turning it up a notch lately is to prime her by holding her arms over her head on the bed and tickling her breasts for a time. Then I fight with her to get her rolled over, and straddle her lower back, facing her feet. Usually, I start by reaching behind me and tickling her ribs. I don't think they yet have words to describe how sexy a woman is when she is kicking her feet up and down trying to put her arches through the mattress. If I glance in a mirror on the wall, I can see she is leaning on her elbows with her shoulders up and her head down and the sounds of tickled woman fill the house.
When she is kicking this way, the way the backs of her upper thighs behave just takes MY breath away. I think this is another time when she has to be nearly insane because it's so fun for me. Before we finish, I usually lean forward and hold her ankles down and get her inner thighs and the backs of her knees. I usually finish by tickling her rear, usually by the handful. This gets her feet going again.
Women are such perfectly constructed creatures, and ticklish ones are even more so. I think mine finds this face-down plan to be an invention of the devil which, of course, makes it intense fun for me, and DEEP down inside. I still like that look on her face, but there is something to be said for that other look as well.
Hiram