Accumulate power, money or experiences. What for? I never understood that.
I'm not sure why you don't understand this. It seems like the most straightforward goal to me. My own experience is that certain experiences are self-justifying: they bring us pleasure or are intrinsically rewarding in themselves. Why they have this property is perhaps tangentially interesting but it is not necessary to know the why to experience the intrinsic rewards. Pursuing experiences that you find rewarding seems like a perfectly good goal to me, I don't know why anyone would feel they need anything beyond that.
Incidentally, accumulating money and power are mostly sub-goals of pursuing experiences. For me, money and power are largely enablers that broaden my options for accumulating rewarding experiences. The nature of the human motivational system is such that the accumulation of money and power can have a certain amount of intrinsic reward but it has often been observed that they are somewhat unfulfilling as root goals. The trappings of money and power are really the attraction, if you can attain them without first accumulating the money and power then that's generally a good strategy.
Really all the other goals you suggest are just sub-goals of the pursuit of rewarding experiences in my opinion, or are intrinsically rewarding experiences in themselves.
My main interest in improving my rationality is to better focus my efforts at accumulating rewarding experiences. The goals set themselves by being intrinsically rewarding, rationality is just a better way to pursue those goals.
Sometime ago Jonii wrote:
When I'm hungry I eat, but then I don't go on eating some more just to maximize a function. Eating isn't something I want a lot of. Likewise I don't want a ton of survival, just a bounded amount every day. Let's define a goal as big if you don't get full: every increment of effort/achievement is valuable, like paperclips to Clippy. Now do we have any big goals? Which ones?
Save the world. A great goal if you see a possible angle of attack, which I don't. The SIAI folks are more optimistic, but if they see a chink in the wall, they're yet to reveal it.
Help those who suffer. Morally upright but tricky to execute: James Shikwati, Dambisa Moyo and Kevin Myers show that even something as clear-cut as aid to Africa can be viewed as immoral. Still a good goal for anyone, though.
Procreate. This sounds fun! Fortunately, the same source that gave us this goal also gave us the means to achieve it, and intelligence is not among them. :-) And honestly, what sense in making 20 kids just to play the good-soldier routine for your genes? There's no unique "you gene" anyway, in several generations your descendants will be like everyone else's. Yeah, kids are fun, I'd like two or three.
Follow your muse. Music, comedy, videogame design, whatever. No limit to achievement! A lot of this is about signaling: would you still bother if all your successes were attributed to someone else's genetic talent? But even apart from the signaling angle, there's still the worrying feeling that entertainment is ultimately useless, like humanity-scale wireheading, not an actual goal for us to reach.
Accumulate power, money or experiences. What for? I never understood that.
Advance science. As Erik Naggum put it:
Don't know, but I'm pretty content with my life lately. Should I have a big goal at all? How about you?