Taipei 101
The first few floors of Taipei 101 are filled with name-brand stores and the last floor underground has a food court with a very wide selection and it even has a supermarket. The atmosphere of Taipei 101 is great, which makes it a great place to walk around, have a meal and window-shop - which is all you can do because the items are so expensive. If you want name brand stuff, you're better off buying it in America and whatnot, since all the stuff has to be imported from elsewhere, which means it'll be more expensive.
To get to the observatory on the 89th floor, you must purchase a ticket. It only takes about 30 seconds to reach the observatory by the elevator, which by the way, is a world record. The elevator is actually pretty cool. When the doors shut, the lights are turned off and these star patterns and constellations glow on the ceiling of the elevator. It's actually really pretty! Not only that, there's an indicator on the side which tells you how long you've been on the elevator and a diagram that shows where the elevator is at in relation to the tower. The ride is somewhat uncomfy because they pack everyone in until there literally is no room, but on the bright side, my ears didn't really pop even though we went up at such a high speed. :)
The observatory is really nice. When you walk in, they direct you to the counter where you may receive your free audio tour guide. The observatory also has a snack bar (mostly ice cream, I think) and a souvenir shop. The view is really nice, but all you really see are buildings and cars.
Overall, I thought it was pretty cool. Like I said before, the atmosphere is really great, though personally I'm not interested in just seeing buildings and cars, but it's still cool. It's definitely an interesting building. Though I've been told that Taipei 101 is an "ugly" building, I would have to disagree. It was built with lots of thought and guided by "feng shui" so I feel that's what makes it unique and interesting. It's pretty cool when you're in a place far away and you can still say "Hey, I can see Taipei 101 from here!" Haha.