When I went to visit the Sky Tree, I got tickets for a few hours later. Good thing was there was Tokyo Solamachi at the foot of the tower! I spend my few hours here looking around and shopping, the mall is still fairly new since it opened in 2012. The mall is very big and come with many restaurants as well. Be prepared to come across big crowds of shoppers though.
Tokyo Solamachi is huge. Features many great shops (the small Ghibli store here seemed to be popular with tourists), a beer hall, plenty of restaurants from around the world, an aquarium, and winter illuminations around Christmas.
It does take a long walk to get from one side to the other, and there are multiple floors, so it is quite easy to get lost if you are bad with directions (like I am). Still, Solamachi is the place to go if you want to spend a day shopping after visiting Tokyo Skytree, and much like last year, I will be visiting Solamachi to do all of my Christmas shopping in one convenient place.