You can stay up until the expiration of your I-94. However, if you plan to leave and then return in about 2 weeks, you will not be permitted to reenter because it will look like you are living in the US and that is not permitted in B-2 status. If you want to stay longer than your I-94, you can apply for an extension of your stay with USCIS. If you provide good reasons for why you need to stay longer, it has a good chance of being approved. Please let me know if you have any additional questions or how I can be of further assistance to you in this matter.
Answered on Apr 23rd, 2013 at 8:56 PM