I don't think it's a good idea to try to plan a second date during the first one, as in set up a specific time and place, but it's ok to talk about common interests and bring up ideas of doing something together sometime in future to gauge interest.
Also, if I'm just visiting a city and meet an attractive girl there, I talk about meeting up next time right away and act more persistent/forward than I would at home, because my time on vacation is much more valuable and I need to know if I should expect to see that girl again or focus on other girls.
Also, if I'm just visiting a city and meet an attractive girl there, I talk about meeting up next time right away and act more persistent/forward than I would at home, because my time on vacation is much more valuable and I need to know if I should expect to see that girl again or focus on other girls.