Oooh, I'd like that different block reward! Maybe for innovation, you could use another algo (yeah, yeah, yet another algo). I'm talking about the popular Jackpotcoin Hash or Talkcoin's NIST5.
Maybe add decentralized chat like Talkcoin does? But let the chat-fee go to the block reward instead of a centralized wallet. So the more chat, the higher the reward. The more miners, the lower the reward. Haha, that would give some nice charts
Don't think there's need for a PoS only stage. Just do hybrid PoW/PoS, so people can keep on playing