I find it quite annoying that when you select a station or a song or anything from the IOS sonos app (S2) it collapses all categories.
To illustrate just search for SomaFM under stations. It will show a few under Sonos Radio (and others too). Expand that section and you will see around 10-15 different ones. Scroll down and select something from the bottom of the list. It plays it but then collapses the whole section so if you want to quickly try another station you have to expand again and scroll.
