Wife and I have had tracfone for years. Never had any coverage problems, since they used AT&T network. Just bought 2 of their smartphones (ZTE) and we are now on Verizon network. If you look at their phones, models ending in G will be AT&T and ending in C will be Verizon. The smartphones are 3x minutes for life so $19.99 for 60 minutes actually gets you 180 minutes talk, 180 minutes text and 180mb data, with 90 days before you have to add minutes.
Didn't know you could get an iphone with tracfone, they don't list any.