What to do in Bangkok?

Planning a trip to Bangkok and was doing some research on what are the "essential" highlights. After scanning through various sources, it appears that the following top the list:

1. Grand Palace
2. Chatuchak market
3. Floating market
4. Spa/massage
5. Patpong night market
6. Suan Lumn (Lumpini)
7. Chinatown?

Have to plan properly and drop some of these in order to maximise the time that I will be there... Yippee! A trip to look forward to :-)