Bangkok is also very HUGE and has many places to see. If you see yourself walking past the same thing over and over again, you are probably going about it wrong. All in all, this is a great place for a westerner to be a westerner, it is very modern.
Insider Tip:If you get offered a tour of the floating market "just around the corner" it is a scam. Bangkok doesn't have a floating market, the legit one is about 150 km from the city. Transportation is cheap if a cab asks you for a flat rate without meter, most of the time he is giving you a more expensive rate than the meter. Always ask for the meter. Sometimes in the more touristic areas you will have to walk out a block or two to find a cab that will use a meter, it is worth it though.