2. bitcoin needs to bring value to society. there needs to be some kind of killer app.
There already is a killer app for bitcoin, or the potential of one, anyway. It's remittances, or the possibility of them anyway. Sending bitcoins to another country is orders of magnitutes cheaper than sending money via Western Union. Even with price fluctuations, you usually come out ahead sending with bitcoin instead of dollars (for example). The only real issue here is that I think not all countries have bitcoin -> fiat exchanges. When that happens, or a large majority anyway, we should really do some serious marketing of bitcoins, for this is really the area in which it makes total sense for bitcoin to totally take over.
As far as the original question, I have a stash of bitcoins that I don't plan on spending. I may trade them if I'm fairly certain I can make a profit (ie, sell high, buy low, and get more bitcoins without spending more fiat). But otherwise, I'm holding these with the hope that bitcoin will continue to appreciate.
That said, I'm seriously thinking of starting a bitcoin-based business, and if it's successful, those bitcoins I would definitely spend. Aside from that, the only time I'd spend bitcoins are in a time where I'm buying stuff off a place like bitcoinstore.com where the price is enough lower than it justifies the bit of a hassle of buying bitcoins over just buying stuff on Amazon. So far, there's only really one thing I want where I'm planning on doing that, a 16 GB RAM chip that was $20+ cheaper on bitcoinstore.com than Amazon. While I can't speak for everyone, that kind of price difference definitely justifies buying a bit more bitcoins to me.