Revisions: How much is too much?

I just read something in a blog about revisions. The discussion was aimed at how much can you revise your manuscript before you suck the life out of your story. I'm starting to feel that way. I've revised the beginning third of my book so much that every time I read it, it feels like a new story. I continue to love my story but thankfully, I'm aware that the insanity must stop. At least until an editor suggests something new....
So now that I've put the first third of my book to bed, so to speak, I'm onto the next parts.
Now I'm focusing on the middle and the ending. Oh, it's been revised before, but not the detailed revisions that include sentence structure, elimination of words and the biggest one for me, emotional consistency.
I love this part of the revision process. Love the tweaking and feel pretty good about the story. But now I need a good critique. This is the time when I start thinking about workshops. I missed Robin LaFever's Plot workshop in San Luis Obispo yesterday due to well, having three kids all in need of mom time. Working on my plot unfortunately had to take back seat to Girl Scout cookies, science projects and camp packing lists. It's hard writing while working and raising a family. Never said that before, but there it is. I find it hard to juggle sometimes. Whew. That felt good.
Anyway...back to workshops. The discussion on our local SCBWI list serve has been Chautauqua. It's a week long (and pricey) workshop that focuses on quality time with distinguished authors, editors, etc. I'd love to go. I heard they offered scholarships.
My friend, Maggie has been to a workshop in Oregon. She had pretty good things to say about it and even got a request from an agent (or an editor?) to submit work once she's ready. I think that's why we all go to these workshops. To hopefully catch someone's eye.
I went to Big Sur last November and loved it. I was lucky enough to be in one of Ellen Hopkin's group. She gave me a 5 minute critique and I swear, everything she said, I heard. Really thought about. The following week, I applied her suggestions to my novel.
Next week, I'm teaching art at my daughter and son's school. Because it's parent conference week, I don't teach at my other schools. I'm looking forward to it but requires some planning. I'll be stepping into an empty classroom with no art supplies or even drying racks. Yikes.
Then at the end of the week, I'm off to Vegas. Yup. I've been a Vegas Virgin up until this point and always thought that I'd go through life without going there. But friendship rules. One of my best gal pals is turning 40 and she's celebrating with a posh cocktail party at Bellagio for 12 of her best couple friends. We're going to have FUN! I am quite certain that'll they'll be no revision time next weekend.