Thor likes to take pictures. Tony got him a digital camera and taught him how to use it. When Thor returns to Asgard, he likes to show Sif and the Warriors Three pictures of modern New York (as well as other destinations.) When he returns to Midgard, he likes to show all the Avengers his photos of Asgard.
While the avengers don’t always stay in the tower together, they all agreed to come in for thanksgiving. Thor didn’t understand what it was so he brought Darcy, Jane, and Sif with the Warriors three. Pepper and Rhodey just happened to show up to make sure tony stayed in line. Natasha and clint brought cupcakes instead of people and bruce cooked. After clearing it with everyone Steve extended an invitation to bucky who showed up right before dinner with an apple pie.