It's not clear to me that Image Analyst's solution answers your question, mostly because your question is not very clear. If the question is, "what are the seven days that individually had the seven largest values?", then that seems like one solution. If you have dates and values, you are better off reading into a timetable and then just sorting by the variable of interest, but either would work.
But if the question is, "which seven day period had the largest values?", then you should create a timetable and use retime to aggregate to weeks, using something like @max as your aggregation method.
