I had sap on my Integra for about two years. I tried every product known to man (and a few that weren't). The only thing that worked was a clay bar. It took forever to do and I eventually gave up (I sold the car shortly after that to buy my 951). I used a flat blade razor (aka glass scraper) to get the sap off the windows. Try and clay bar and be patient, it's going to take a while but it will be worth it.

 

Don't park under a tree. Eventually sap will ruin your paint.

 

Acetone on a rag and then gentle rubbing to affected area.