I know that the talmud states that one can leave Israel for Parnasa, for marriage, and for Torah study. Leaving Israel to see family is also permitted because it falls under the category of Kibud Av Ve'em. Is it however permitted to leave Israel in order to travel and see sites like national parks or landmarks?

I believe that it is permitted to go on holiday outside of Israel only if one's general emotional health will be enhanced, or if there is a specific need for the information to be gained. For many people, getting away from the pressures of Israeli life and learning about other places certainly enhances the quality of life and I would consider this a benefit to emotional health.