I will add my $0.02 here. I don't use PL for business travel for the following reasons, in descending order of importance:
1. No flexibility when meetings get rescheduled/cancelled
2. Distance to my destination. Often I am in a unfamiliar city with an early morning meeting. I want to stay within 1-2 miles of my destination to avoid getting stuck in traffic and miss my meetings (PL let you pick a general area, but it could still be far away or with confusing roads like Boston)
3. There are a lot of trips when a few of us travel together. It makes no sense to use PL which can get you in different hotels.

I don't use PL for personal trips because:
1. location, location, location. We have a young toddler travelling with us. I don't want to push his stroller for 20 blocks to the next place I want to visit.
2. There can be huge differences between 3 stars and 3 stars, even of the same brand
3. Because of my business travel, usually I don't have to pay for personal stays anyway.