It is basically always better to run more APs at lower power in the areas where you need coverage, than to boost the power. Especially today with the radio spectrum being so congested.

Despite this, I could expect 3-5 people to hunt me down at PyCon when I was running the wireless to tell me that I had misconfigured the wifi because it was set to low power. More reports of that than reports of wifi not working, IIRC. ;-)

(I was running the wireless because the people we paid do to the wifi would just set up one or two APs and crank the power)