When running a Smart List for "Visited Web Page" there is a note at the bottom of that filter that says "activity of this type is archived after 90 days". Would it be correct to say that if I set the date of the report for 180 days that I am only going to get half of the data I am looking for? If so where do I get archived data for website activity? Here's a screenshot of the report I am attempting to run. 2016-05-17_0910 - ErikGroth's library
There is an option to increase the timeframe for which you can retain the web page visit and change data value activity. Please check with Marketo support.
Additionally you can always filter the lead activity log results to show archive data, I am not sure how to achieve directly in smart list filter for visit web page.