I am fortunately enough to have a RTW business class ticket (paid) for my honeymoon, on 2 of the legs, BKK to ZRH and ZRH to NYC. I am flying swiss. I am *G on united but have no status on Miles and More (i am a member with a couple of thousand points). I know some airlines, UA and TG offer the opportunity to upgrade on checkin sometimes quite reasonably using cold hard cash (as opposed to points status etc). Does anyone have any experience with upgrading on Swiss from business to first using this method. I'm especially keen to do it from ZRH to JFK as it's their new product and supposedly their first lounge in ZRH is meant to be really nice?

Thanks in advance