It needs to be said...
Sir, you are a danger to yourself and others. Think about taking two weeks off and then quit. This thread should have been moved to the homeowner forum after your first post. Homeowners - everyone, in fact - are certainly welcome here. It confuses people who are trying to help you when you contradict yourself. I can not tell if you are unwilling or incapable of following some of the advice that has been offered...or if your posts are a ruse. You deserve an "A+" for industriousness but that's about it.
You lost me at the beginning where you said "...east of Philadelphia where cool grasses seem to do well despite the luxury of a sprinkler system for the scorching months of July and August."
If you do go with the Roundup you will be able to turn the water off altogether and won't need to do anything else until Labor Day, but I am not recommending that. Consider hiring someone. A small owner-operated lawncare company offering individualized care is probably your best bet - organic or synthetic is your choice. If you make the call Monday I dare say you will be a happy man by mid-September with a lawn in good enough shape that you can take care of yourself next year if you do a lot of reading here between now and then.