Custom Menus and Privilege Sets should work for you.
I need to clarify. I looked into Privilege Sets. I want the users to be able to get to the layout but only through the use of a scripted button I created (based on the value of a drop down menu). I don't want the field staff users to be able to navigate to a particular layout by selecting it in the layout menu, however I want the layouts available for managers to navidate to. If I use privilege sets and set the layouts to "no access" when the field staff click on the scripted button it will take them to the approriate layout (based on the value of the drop down menu field), but they will see "no access". I want them to enter data on the layout, but not navigate through the layout menu...only the scripted button.
I'm looking at custom menus, but I don't see how that will help either.
I thought maybe there was a security setting that I'm missing that defines which users see what layouts in the layout menu. For example: if user is "field staff 1" they can see only layouts 1 and 2 in the layout menu. If user is "manager 1" they can see layouts 1, 2, 3, 4, and 5 in the layout menu. However "field staff 1" have access to enter data on layouts 3, 4, and 5 but only navigating to it through a scripted button.