Half a year ago i applied for a US tourist visa to see my boyfriend (now husband) and to travel throughout US. I was told almost exactly same things as the comments here. And by all means they had the right to think i would get married and change status (well i did get married but didn't apply for status change)

If you are just travelling to your brother's wedding, i don't think there should be much of a problem. (I was applying from indonesia, where i was living for years, so maybe here the process is different)

It will all depend on the interview and how prepared you are. (no one really checked my supporting documents, but it definitely pays off to bring them in).

Does your wife have enough ties in here, that she can properly prove that she will come back? Do you have enough ties in thailand that can prove that you will both come back?

For my tourist visa application, it took me about a month from the day of application to getting my passport back. but that drastically varies on the embassy appointment schedule.