Please Advise. F-1 (student) Or B-1/b-2 (business/tourist) Visa For 2 Months Of Usa Study?

[peacetime]

Friends,

Any advice you can offer would be appreciated. Thank you.

31 year old female Thai recently received a Canadian visa to study business english in Canada for 2 months.

She would like to spend 2 additional months studying business english in the US as well.

Question:

Would she be better off getting an I-20 and applying for a F-1 Student visa? Or would she be better off applying for a regular tourist visa, or even a business visa?

The Particulars:

Graduated from good Thai University. From small town. Fluent English.

Successful Real Estate Salesperson for an expat developer in Thailand since 2004.

Developer has given her a 6 month sabbatical (in writing explaining her salary is 500k baht base, with 500k in expected commissions.)

She has 500k baht in her bank.

Owns 2005 sedan she bought new and has been making regular payments on since.

Rents small home.

Past Visa Applications:

Turned down 5 times for US tourist visa from 2001 to 2003 in naive effort to visit American boyfriend.

Spent a month in New Zealand in 2003 on Tourist Visa traveling.

Spent 6 months in Canada in 2004 on Tourist Visa studying English.

Visited Hong Kong, Singapore, and Shanghai in 2007 and 2008 for work related trade shows.