Hi, I advise you to visit such places...
Tropical garden "Nong Nuch".... Here you'll see the hugest park with greenhouse with orchids, traditional Thai show, show with elephants, park of palms and cactuses, museum of precious stones and jewellery factory. For 8 hours you need pay near $10-$15... I think it's not too expensive... ;-)
Also I liked Discovery-Tour. There are sea aquarium, hill with monkeys, unusual buddhistic tample of Hades and Heavens, the biggest garden of butterflies on Asia, and also dinner is included... ;-) it costs near $25 for adult, and near $13 for children.