I used to be a subscriber to Spotify, back when I had to jump through crazy hoops to be able to subscribe to it from Germany (involving a VPN, entropay and paypal with a fake address).

I have since moved on to Rdio, which does not have as good a music selection (in Germany) but this awesome "artist radio" feature, which is kind of like Last.fm or Pandora, but better. I absolutely LOVE this feature.

Does Spotify have something like this? It did not when I last checked.

Also, does the iPad app work with AirPlay without going through the multitasking switcher?

I think Spotify has by far the best music selection out there. Also, that high-quality option is very much appreciated.