South America hlep please!! Thanx

OK, here's the scoop. My family and I are definitely going to South America this summer, June and July, for 2 months. We are a husband and wife, two kids under 10, and a dog. We don't want to be anywhere where the average temperature will be below 55 or 60 degrees, and the only two countries that are definitely out are Brazil and Columbia. Finally, we would like to be in a city that is large or fairly large so that there will be plenty to do. Most importunely, I would like for it to be safe as my wife likes to take the kids out during the day but I can't always be with her. Where would you guys recommend that we go? Thank you SO much for your help. I would really be very appreciative and thankful for any type of help or suggestions. Thank you. [email protected]