I typically use at least 3gig a month myself. According to the Verizon usage breakdown steaming music only makes up a small part of that.You guys have some small data plans.
Streaming Pandora all day at work (not on wifi) and I use about a gig a month.
Its about the only data I use outside of maybe 100mb for email over the course of a month, but even still, much below the average data allotment for almost all the major plans.
I also prefer Pandora to the other options. Tidal just seems expensive and based on unicorn farts and rainbows. Spotify seems to crash a lot for me. Rdio is supposed to be cool but I haven't tried it.