I don't know that you would want to bother changing planes (and reservations) at FRA to continue on to WAW, but DL can get you to JFK to take SQ to FRA for 90k business/100k first. It's one of the few good values left in their award chart, and it's going away mid-May 2010. You can ticket through then for travel through mid-May 2011.
Excuse my newbie question. But what does SQ mean in this context? I search for it and SQ seems to refer to Singapore Airlines, which I do not believe you are implying for JFK-FRA travel.