What excites me the most about SpaceX and Elon Musk is not so much the superficial/ostensible meaning of what they're doing (private contracts to deliver payloads to space) but the following. The fact that a foundation is being laid for a situation where basically a single guy, a private citizen, namely Musk with his personality and talents and passion, can one day slam his fist down and say, "That's it. Fuck it. We're going to Mars." and then make it happen. Putting humans on the surface of Mars. Or an asteroid, whatever. As completely private missions, if desired. Without getting bogged down by a flaky showboating Congress, by NASA budgets, by legacy bureaucracy, etc. Because they're building (incrementally) a complete in-house stack for taking people off-planet and (eventually) to other ones, and back. Yes you have to make the money work. That's doable. But more importantly it reduces their exposure to bureacracy, government and BDC inertia. And it's not a baby-vs-bathwater situation. They can hire away the brains from NASA and other space companies, where needed, where possible, so it's not like they're losing out on all that accumulated experience and best practice. But they do get to start from scratch and make it much easier to greenlight new "risky" projects and Get Things Done.
Planetary Resources excites me for similar reasons. Though I don't think they have quite the same degree of talent at the top in a single guy as with the case of SpaceX. But still, very promising team, vision and approach.