Profits Per Partner is probably about the best inverse measure of QOL you can find. The higher profits per partner, the more they squeeze out of each associate. Unless you're hell-bent on making partner and accumulating as much money as possible, you don't want a high-PPP firm, and if you're in a career so much for the money, you may be better suited to i-banking.
DISCLAIMER: This post is not legal advice. Alamo disclaims any and all liablity for interview gaffes, disastrous career moves, mid-life crises or other consequences of following the advice given above.
NALP already has the numbers for all BIGLAW firms re summer associate offers. Don't ask a question when the answer is available online.