I'm at Pad Thai Thip Samai, arguably the most famous pad thai place in the city. It's located in the same area where the Grand Palace is, and can be pretty hard to reach via BTS. Just hop on a cab or tuktuk and tell the driver "Pad Thai Pratupi" (which translates into the rather macabre sounding "ghost gate pad thai"). Most of them should know where to take you.
Rather than sticking with regular pad thai I have ordered a fancy version, pad thai haw kai goong sot, or jumbo prawn pad thai wrapped in an egg. There's an English menu with pictures so you don't have to worry about ordering. I saw more tourists here than at Platinum hahaha.
Be sure to try their orange juice, which is famous in its own right. Apparently the queen of Thailand loved the pad thai here so much that she gifted the restaurant with her secret recipe for orange juice and so they started selling OJ along with their pad thai. Sounds a little random and bossy to me (Would you dare not to sell OJ created and imposed on you by the queen?) but I'm sure the queen meant well. In any case the OJ was refreshing and sweet, so just go with it.
The pad thai arrived and looked awesome. Felt like I'd received a present wrapped in egg, and I saw the envy on the faces of the Korean mom and daughter pair seated next to me, both of whom were halfway through their regular pad thais. Go big or go home, girls.
Taste-wise it was meh. I didn't like how sweet the very orange noodles were and there wasn't enough wok hei (fragrance) in the dish. Underwhelming, but the queen's OJ saved the day.