I love the giant dragonfly tour because it earns 20 medals max when you're on your own. It makes life so much easier when trying the save up medals quickly, only I wish it wasn't such a rare encounter.
You can go on Club Tortimer which is a multiplayer version of the island that sets you up with random people who are also on Club Tortimer, but sometimes you find creepy people/young kids/other people who you may not necessarily want to play with, so it's probably best if you just went on here and asked people here if they'd want to go to your regular island together.