It's probably way too early for this topic, but I recently listened to a Grape Radio interview with winery owner Calude Blankiet where he described winemaker Helen Turley's process of deciding when to harvest. Blankiet says that Turley likes to taste the juice at home in the evening. She prepares a must sample, allows it to macerate on the skins, chills the sample and then tastes it in the evening out of a wine glass. I've heard of winemakers tasting the berries in the vineyard and using this to inform their harvest decisions, but this is something else altogether. While she's tasting, she also reads the lab reports, which would have been prepared that day and delivered to her. Must be nice.
I'll have to do my own lab work at home with a hand refractometer, a hand pH meter, and a cheap acid test kit that feels like some high school chemistry project, but I see no reason why I can't try her must-in-a-glass technique. Tasting the juice while you're relaxed in the evening rather than sweating in the vineyard and spitting out seeds might allow you to evaluate with less distraction.
The entire interview is worth a listen as they spend the time walking Blankiet's vineyards. The section where he talks about Turley's harvest decision begins around the 20 minute mark. Those guys over at Grape Radio do a brilliant job, putting out a new 40-minute show every week. Their archive page is loaded with interesting interviews on just about any subject you can think of.