Married filing jointly means income for both the US citizen AND the spouse must be declared - not something I would do. Why add to taxable income if you don't need to do so? This also involves an election to have the NRA spouse treated as a resident alien, and again, there would be few/no advantages to this IMHO.
Check this link for specifics:
http://www.irs.gov/Individuals/International-Taxpayers/Frequently-Asked-Questions-About-International-Individual-Tax-Matters#FilingStatusandDependentsFiling Status and Dependents
1. I am a U.S. citizen married to a nonresident alien. What is my filing status and can I claim an exemption for my foreign spouse?
In general, if you are a U.S. citizen or resident alien married to a nonresident alien, you are considered “Married Filing Separately” unless you qualify for a different filing status. If you pay more than half the cost of keeping up a home for yourself and a qualifying child or other relative, you may qualify for the head of household filing status.
If you are a U.S. citizen or resident alien married to a nonresident alien, you and your spouse can choose to have your spouse treated as a U.S. resident for all U.S. federal income tax purposes. This allows you and your spouse to file a joint return, but also subjects your nonresident alien spouse’s worldwide income to U.S. income tax.
For more information on the filing status requirements, see Publication 501, Exemptions, Standard Deduction, and Filing Information.
If you file a joint return, you can claim an exemption for your nonresident alien spouse.
If you do not file a joint return, you can claim an exemption for your nonresident alien spouse only if your spouse has no income from sources within the United States and is not the dependent of another U.S. taxpayer. (Emphasis mine)
In order to take the exemption, the spouse must have an ITIN.