Due to long site names in some cases where site names nearly reach 255 character length, Site names are partially hidden on Tableau Server landing/logon page or Site Switcher page for administrators.
Couple of points that could be a feature enhancement request.
* A site picket drop down resize should help specifically when site names are almost 255 characters in length
* A dynamic horizontal scroll bar should be displayed if site names exceed width of current drop down window
* A 255 character width site picker or site switcher window by default
It will be a good choice to have resizeable drop-down for Site Picker at logon and Site Switcher window in Tableau Server.