When my husband was in college he spent one summer in Nantucket washing windows. He and some friends stole some ladders (bad but true) and printed up some cards with the clever catchline, "A dirty window is a pane in the glass" (they were English majors). Apparently there were a lot of takers for a bunch of cute, hungover boys to come over and wash windows that summer.
I'm reminiscing over this because this past weekend, Oliver and I washed the big windows in the front of the house. We had not done it since we moved in over 4 years ago.(They are high up and huge). We did eight in all which took a few hours of pretty hard work (four on the main floor and four on the second floor). We have the type of double hung windows that pivot in for cleaning. It was definitely a two person job because they are heavy and unwieldy, but, what a good system -no ladder required! We used plain vinegar and water with a squeegee, which worked fantastically well. Like forget Windex, ever, after this experience.
The difference is really remarkable. It is SO worth it to either clean 'em yourself of hire somebody to do it. I can't stop talking about how good these windows look!