If you're looking to tie her wrists straight up above her head then sticking a chin-up bar across the top of a doorway might not be a bad way to go. Those things are built to take a hell of a lot of weight so a wiggling 'lee shouldn't be a problem. You could lash one across the bottom of the doorway as well for tying her ankles to to stop her moving at all if you're a dirty control-freak like me, plus if you get the retractable kind you can take them down when you've had your giggles and stash them until next time. You can get fairly decent chin-up bars for between seven and twelve quid that will do the trick.
As for personal preferences, I like being tied to chairs Reservoir Dogs-style, hands behind the back, ankles taped to the legs, keeps me restrained and has the added bonus of makng my feet difficult to reach (though why anyone would put their hands near those biohazards is beyond me). As a 'ler I'd have to go with the good old feet out front, hands above the head; the "missionary position" of tickling fetishism. Purely because I am an unimaginitive sod and very easily pleased.