What are some other interesting ideas?
For primary motivators that make us want something we'll visit Mr. maslow:
- Physiological
- Safety
- Love/belonging
- Esteem
- Self-actualization
In our time, a lot of the above can be fulfilled with excess money. Once you have the money you can decide how to fulfill your various other needs.
But if you go back in time and, for instance, try to gain the respect of others, find your ideal mate, learn what really happened that the historians glossed over, you can't necessaily fulfill your other needs.
To a degree, money is the "stem cell" of our society - it can be turned into anything. So it makes sense to essentially "wish for more wishes."
I think your rule about not changing the future precludes that, though. At that point, you might as well say that you have a quantum telescope that allows you to view any point in history - because any participation would alter the past/future.
But that's not nearly as much fun as wishing for more wishes.