OP, I've actually been in Bangkok the last six days. I'm currently in Tokyo waiting on my flight home. You won't need a chip and pin card. Retailers that do take credit card have no problem with standard magnetic strip cards. Be careful using ATMS, as there is a 180 Thai baht fee to withdraw money. It would be wise to bring cash with you because there is no commision fee to exchange dollars to baht, and the larger the bills the better the rate (at least at smaller exchange places in the city), at the airport I didn't notice better terms for larger bills. Exchanging dollars in town might yield a better rate vs. at the airport - but not by much.
Ensure you have plenty of baht on hand because some places that do take cards impose a minimum charge to use a credit card, 200 baht was the lowest minimum I saw. If you're going to be in Bangkok and use the MTR and/or BTS, please know that the three day pass for the MTR does not work on the BTS, and you will need cash only to purchase tickets, the machines don't accept credit or debit cards, nor do the humans at the airport.
In all honesty, I found myself using cash most of the time.
If you visit any pharmacies and need to bring back any prescription drugs, Boots and Watsons are more expensive than indepenent pharmacies but they take credit cards where as the latter is cash only, and make sure it's an air conditioned pharmacy. I nearly died when I saw a contact lens kiosk at the Sala Daeng BTS station selling lenses in the open heat.
Hope this helps.
