As a teacher, I think two weeks is perfect. Most teachers only have solid plans about a week out, but they will try for longer when asked. Also, be certain to have your kids ask about anything else when they come back too! (many people forget this!)
A few more points: It is very hard to know exactly how long a lesson is going to take, especially when unexpected things happen. In all school districts across the country that are already in session, I can guarentee the hurricane had an impact on what teachers were able to cover this past week. (though maybe less so at the elementary level) Lessons get changed. For example, SS teachers might have done a spontaneous lesson on hurricanes, or the geography of the Gulf, to address questons that there students had. But even during normal times, some lessons take longer from year to year.
The two things (some of the few things) that really drives us crazy is when parents give us less than 24 hours to gather work, or when the kids don't do the work that is given.
It is a big deal to gather a week's worth of work for your child. It is very time consuming, and it means that we have to neglect the needs of all the other kids. Many parents don't understand that we can't just stop class to gather work. We have to do it during our planning time, and many teachers only get one a day. So if my planning is from 7:30 - 8:30, and you call at 10 am, I may not be able to gather the work until the following morning, especially if we have a staff meeting after school.