Tod, it seems like 30-day visa exempt will be quite sufficient. If I read you right, that will work fine depending on exactly when I arrive for a definite 11 Feb. departure.
To clarify, if I have to go to Singapore, it may be on 14 or 15 January for as little as day and no more than two days. When I fly back to BKK, I won't be staying there beyond 11 Feb.