sunderi said:
I think the answer to this is going to vary greatly -- it's really a matter of personal opinion.
Personally, I don't mind at all if someone tries something "experimental" on the dance floor.
However,
Don't keep trying it over & over again if it doesn't work
Don't try to TEACH it to your partner, unless she asks
DO try it again if she asks you to -- she might have ALMOST gotten it and want another shot at it 
Totaly agree with sunderi, and totaly disagree with clave (sarry

)
First off, the answer is going to vary greatly, it's really a matter of personal opinion. The only catch is, it's not a matter of your own personal opinion, it is a matter of the follow's personal opinion, on that particular night, on that particular song.
If she is in a romantic mood on a romantic song, don't go and try that fancy double-spinn-armlock-to-underebelly-headturn-to-dip-to-one-handed-quadruple-spin thingy.
Other than that, I agree fully with every aspect :
- don't try it over and over if it does not work. This is a social dance, not a practice session. Besides, it is always nicer to try it with different follow to figure out if your lead was wrong with the first follow or if she simply did not get it, before changing everything.
Hoever, if you do want to figure how to do the move, you can always ask your follow at the end of the song if she'd be willing to try and figure it out with you, some really love giving their input on things, because precisely, in classes they have reached a plateau and it becomes boring. But inventing a new moove, telling how best to lead it for her to understand what's coming next ? That's exciting !
- don't try to teach your partner, well, I'd say don't try to teach her at all, because you are the lead, and if your lead is clear, she should not need to be taught the moove. But, sometimes it's nicer for her to be involved in the creation of the move, see my answer right above
- Do try it again if she asks you to, after all, you are here to please her, aren't you ?
Now, on to clave's answer :twisted:
The main reason I disagree with you is that I do not see dance as something you learn by the book, take notes, store them, cehck them out, and so on...
Dancing is, well... dancing ! Of course you nedd the proper technique to lead, the proper frame, the proper way to move. But then what ? Is that all there is to it ? It's all only a shell, really, what is important, what really matters is how you fill it !
Let me use a metaphore to explain myself best : When you learn a language, you are tought full sentences. You get to learn the gramar behind it so you can construct sentences your self. Then you learn new words. You also learn how to make phonems, and how words are constructed. After that, you are on you own : if you don't have anything to say, anything to share, then what is the langage except for an empty shell ? On the other hand, if you have a story to tell, and make up a new word here and there (but using the basic rules and sounds) that I can understand the meaning of, I'll have a blast listening to you and I'll come back for more !
Dancing is basicaly the same : every moove you learn can be cut down to elementary moves. And there can only be so many new "elementary" mooves. Once you have done that, well, it is like you have been given an alphabet, or a dictionary. The story is now yours to tell. The follow is ready to listen to it, and the music allready sets the mood...
You're dancing with your emotions, and for it to really be a terrific experience, you need not to bind yourself inside a strictly defined amount of patern you should not deviate from, you nedd to know that whenever the music is right, you can switch from that begining to that end, and the transition can be... well, let's just make it up as we go !
Freedom is what will make your dance special, diferent, tastefull. At least, to me, it is the starting point to defining one as "advance" dancer : the ability to improvise a move. Besides, it is also what alows you yo have a blast at a live event : since the musicians are changing the music according to the way people dance, and people are reacting to it...
It becomes more than a dialogue, it is an all out conference to make up a huge story, and it is a wonderfull thing to experience