Keep the settings per the last session (pan vs select)
As someone who has getting older and hard to see the tools, it would be spectacular if I didn't have to toggle to the pan button every time I open a PDF. Who want to select things by default in a PDF? Or at least have a preference so the user can select the desired tools to be set. I work with large plans, and it's my preference to be able to pan by default. I don't want the select tool active as it can select lines and get inadvertently moved. All you need to do is in Customize Toolbar, allow the user to swap out any tool flyout and select the desired one. That it! Easy right? A couple of seconds each pdf x 100's and ultimately my sanity.