I have described a simple way to configure the AWStats web-interface last month,
so I will continue this topic further and tell you how to add a menu to quickly switch between configured sites.

You need to set to true the UseFramesWhenCGI AWStats configuration directive. Then, the whole process is based on left frame modification, which can be achieved by editing HTMLTopBanner function located in /usr/lib/cgi-bin/awstats.pl file.

Simple menu

AWStats menu defference.

AWStats - Simple menu

The following modification provides a small and straightforward static menu.

--- awstats.pl  2016-05-04 21:30:39.689655190 +0000
+++ awstats.simple.pl   2016-05-04 21:16:59.327708554 +0000
@@ -9835,6 +9835,14 @@
                        print "</td>";
                }
                print "$lt;/tr>\n";
+               print "$lt;tr>";
+                print "$lt;td class=\"aws\">";
+                print "Other: ";
+                print "[$lt;a target=\"_parent\" href=\"/awstats.pl?config=sleeplessbeastie.eu\">www</a>] ";
+                print "[$lt;a target=\"_parent\" href=\"/awstats.pl?config=blog.sleeplessbeastie.eu\">blog</a>] ";
+                print "[$lt;a target=\"_parent\" href=\"/awstats.pl?config=repository.sleeplessbeastie.eu\">repo</a>]";
+                print "$lt;/td>";
+                print "$lt;/tr>";
        }
        if ( $FrameName ne 'mainleft' ) {
 

Advanced menu

AWStats menu defference.

AWStats - Advanced menu

The following modification provides a more advanced menu without duplicated entries.

--- awstats.pl  2016-05-04 21:30:39.689655190 +0000
+++ awstats.advanced.pl 2016-05-04 21:30:12.386589742 +0000
@@ -9835,6 +9835,13 @@
                        print "</td>";
                }
                print "</tr>\n";
+               print "<tr>";
+                print "<td class=\"aws\">";
+                foreach my $tempSite ('sleeplessbeastie.eu', 'blog.sleeplessbeastie.eu', 'repository.sleeplessbeastie.eu', 'survey.sleeplessbeastie.eu', 'debian.sleeplessbeastie.eu') {
+                       if ( $SiteDomain ne $tempSite ) { print "<a target=\"_parent\" href=\"/awstats.pl?config=$tempSite\">$tempSite</a><br/>"; }
+                }
+                print "</td>";
+                print "</tr>";
        }
        if ( $FrameName ne 'mainleft' ) {

You can apply these patches using patch utility against awstats 7.2 (build 1.992).

Downloads

awstats.simple.patch

awstats.advanced.patch