My fiancee (Be) received her fiancee visa finally, and we're going to the US in April, planning a June wedding. We'd like to be able to come back to Thailand for a visit; my question is, what's required? Is there a period we must wait before coming back? Special paperwork/fees required? Any info appreciated.

Lung Ling,

I know very little about US visas, but after a bit of Googling I found the State Department website.

I am assuming that Be has a Nonimmigrant Visa for a Fiance(e) (K-1). In which case the website says

Can a K-1 Visa Holder Leave the United States?

The K-1 visa allows a fiancé(e) to enter the United States one time only. If you leave the United States after entering on a K-1 visa, you may not re-enter on the same visa. If you want to leave and re-enter the United States, you should apply with Form I-131 Application for Travel Document to the USCIS office that serves the area where you live for advance parole to return to the United States. See Emergancy Travel  for information on how to get a travel document that allows you to return to the United States.

I haven't followed all the links, but it looks like she can't leave unless it's an emergancy, I'm afraid.

If you read through the above link you will see what needs to be done after your marriage for her to become resident, travel outside the US etc.