When you create portraits that will run together you can create a “feel” for the portraits.  One way is to use a traditional formal portrait where the backgrounds are identical.  Another way is to use a similar style.

   

The last three photos are more traditional.  But when used together they are not very good as a theme.  What you need on a company website or organizations website is consistency of portraits.  My recommendation is to find a theme and then have all the portraits done the same.