Best way to limit what URI/Path is available

This can be optimized using switch statement. Create string datagroup (example2_allowed_uri) for allowed uri. You can use default_pool to send traffic at the end or reject it if there is no match for the HOST.

when HTTP_REQUEST {
    switch -glob [string tolower [HTTP::host]] {
        "example1.mydomain.com" 
       {
	     pool /Common/App_Example_1.app/Pool_Example_1_pool
	   } 
	   "example2.mydomain.com"
	   {
	     if { [class match [string tolower [HTTP::uri]] starts_with example2_allowed_uri ] } { 
		 pool /Common/App_Example_2.app/Pool_Example_2_pool
	     } else {
		   HTTP::respond 200 content "access denied" noserver Content-Type text/html Connection Close
		 }
	   }   
	   "example3.mydomain.com"
	   {
	     pool /Common/App_Example_3.app/Pool_Example_3_pool
	   }
	   default {
         pool default_pool
      }
    }
 }