1 ) Golden Palace, 2) boat ride on Ao Phrao river with visit to Temnple of the Dawn, 3) Night time at Patpong, try Kings Castle, otherwise avoid all upstairs bars.
If you're fond of shopping then try and get to the Chatuchak (weekend) market which is to the north of the city close to the northern bus terminal. Get there early as you can as the heat can be oppressive in the little alleyways. I can only manage about 3hrs max here but you can buy practically anything from buddhas and amulets to clothes, housewares, food, cds etc etc.