Baiyoke Sky Tower
Anyone can visit the public observatory on level 77. The view is amazing: you will see the various expressways and neighborhoods of Bangkok, the royal palace and the Chao Phraya River. During the day the view can be quite smoggy, so it's better to visit at night to see the city all lit up. For a classier experience head to the Roof Top Bar & Music Lounge and 360 degree revolving roof deck on the 83rd floor. The view is better but you'll either need to pay an admission fee or buy pricey drinks and dinner.