Back when I was an iOS user, I used GoMusic as well, but if you're looking for a few more features and generally a better looking UI, I'd recommend that you guys use gMusic -
Link. I always thought it loaded faster and the dev was more reliable with update; it also looked great on the iPad. Downside is that it's a $1.99, but if you ain't using Installous...well, do you.
For all the tinfoil hat wearers out there, I'd suggest
Audio Galaxy. Basically, as long as you keep your computer on 24/7, you can stream your entire library from anywhere.
Personally, I got about 100GB on Google Play Music, and since I was already in much of Google's ecosystem, getting a Galaxy Nexus was a pretty wise choice for me.