Eitehr way, an idea for a new tourist-mechanic could favourably hook into the citizens mechanic, particularly their expectation-rating;
opportunities for tourism could benefit the approval of the tourist citizens, such that the ones with high expectations would "expect" to access appealing tourist locations be it inside the own empire or on firendly alien worlds that shared open borders (or some manner of tourist treaty?).
once tourism occurs, it would give wealth to the host, as in previous games...