I'm Swedish and would like to go to the US for a two week holiday with my wife, who is a Thai national.

What type of requirements apply for her to be able to get a tourist visa for two weeks?

As she is just going for a visit, she may apply for a Visitor visa. See also Visa Information For Temporary Visitors, in particular, Denials and Ineligibilities and Waivers.

As a Swedish citizen, you may be able to benefit under the Visa Waiver Program (VWP). You may need to renew your Swedish passport first, to satisfy the United States' passport type requirements.

This should be pretty easy. Do you live in Thailand? If so, do you have work permit and visa? What you need to prove is your ties will keep you from staying in US and her ties to you (marriage cert, joing bank account, property, etc) will have her come back as well.

TH