I'll second the view on Alexa De Paris; it's wonderful. And nice to see someone else compare his playing with FZ. I'm a huge fan of both and have for a long time thought the same rather than the usual comparisons with Hendrix which you read about.
Back to the b sides, if you can find them, check out the full length versions of;
Shockadelica
La la la, he he hee
B sides to If I Was Your Girlfriend and Sign O The Times respectively. La la la, He he hee even has a bass solo..., played by Prince..., but only on the full length version!
The extended versions of Raspberry Beret and Mountains in particular are also well worth seeking out.
17 Days, the flip to When Doves Cry, I think is fantastic and She's Always In My Hair, b side to Paisley Park is possibly my favourite Prince song but then there are so many to choose from.
In summary then; if you're in a record store and see a Prince 12". Buy it!