Sirius users, is it better to buy the streaming subscription for multiple users?

[funmoneypit]

My wife and I both have Sirius radio in our DD's. I do the every sixth month threaten to cancel thing and then get the 6 months for $30. It's kind of a pain to do it for both of us and we are still paying over $120 a year for both vehicles. Sirius has the streaming subscription that you can use a phone or tablet or whatever mobile device. Obviously we can use Bluetooth to stream it in our cars plus we could use it in our boat and our home sound system that has Bluetooth. Probably would end up cheaper even doing a yearly subscription. Anyone get just the streaming subscription? Can you use it on two devices simultaneously as in both of us have it on our phones driving at the same time? Any input is appreciated!