Do Bangkokians speak English regularly?

[Donald_Morgan]

I don’t speak any Thai, though I would certainly be willing (and hopefully able) to learn some if I’m living in Bangkok for a few years. Will I be able to get by day-to-day speaking English?

[Manuel_Sguazzi]

Yes. People in Bangkok and in other tourist destinations in Thailand can speak a basic but decent English. And that is valid for daily life (taxis, restaurants, bars...) and for business life, since most of the people working for companies with offices in Bangkok can speak some English.
You may find some trouble with communication in the countryside, where people are not so familiar with English.
In any case, a basic knowledge of Thai will be well perceived by the locals and will allow you to better experience your stay in Bangkok.

[Jeng-Chyang_Syu]

IMHO of course, Bangkok is among the world's mega cities and English is more understood thanks to globalization.

[Robert_Taylor]

Depends on the level of English you desire and what area that you are in. Bangkok is a city of over 10 million people of whom probably more than half came from the provinces. English as taught in Thai schools is rote learning of reading and writing so very basic and no speaking skills to speak of. Those in the service industry in the hi traffic areas usually can speak basic english but you are not going to have any long conversations. If you actually plan on staying here a while, then take the first couple of months and go to language school. You will be very happy you did and your stay here will be a lot more pleasant and productive.