My staples when in Thailand:

Pad Krapow with squid, shrimp, or mixed seafood (must have at least once every 48 hrs)
Kaeng Pa (jungle curry) with squid, shrimp or seafood
Chicken Fried Rice
Green curry w/chicken
Larb Pla Dook
Som Tom (only from street vendors)
Many other very spicy stir-fried meat/veg dishes w/steamed rice
Many other soups

Pad Thai is good, but just seems so unhealthy compared to other options. I try to sample one new dish every day or two, and am rarely disappointed. I DO NOT like mangoes or sticky rice at all, or anything containing the sweet red gunk known as "chili sauce".