When you submit a form, only the value of a select control gets submitted. Not the displayed item. That is a limitation of the HTML control rather than struts.
You could always have an onclick event on the select box that copies the "display value" into a hidden field whenever you select an item. That way you could get id AND value.
Or store a list/map at the server end (in session scope) and use the value to look up the display string.
Hope this helps,
evnafets