Can I pick a date range for most viewed products and top searches?

Not at the moment. Most viewed products and Top searches have no date picker. They cover everything recorded since you switched on tracking under Personalization.

What each list shows:

• Most viewed products: the 20 most viewed products, each with its number of views and how many different shoppers viewed it. Products are listed by their product number.
• Top searches: the 20 most searched words or phrases, with how many times each was searched.

To open them, go to Marketing → Marketing Home, click the Personalization tile, and open the Insights tab.

For date-based shopping data, such as cart additions and checkouts, use Analytics → Reports and search for Customer behavior.