Io ho impostato il virtual host così e tutto mi funziona:
<VirtualHost *:80>
# The ServerName directive sets the request scheme, hostname and port that
# the server uses to identify itself. This is used when creating
# redirection URLs. In the context of virtual hosts, the ServerName
# specifies what hostname must appear in the request's Host: header to
# match this virtual host. For the default virtual host (this file) this
# value is not decisive as it is used as a last resort host regardless.
# However, you must set it for any further virtual host explicitly.
ServerName miosito.test
ServerAdmin info@miosito.test
ServerAlias www.miosito.test
DocumentRoot /var/www/miosito.test/public_html


<Directory /var/www/miosito.test/public_html/>
Options Indexes FollowSymLinks MultiViews
AllowOverride All
Order allow,deny
allow from all
# AddHandler php-cgi .php
# Action php-cgi /cgi-bin-php/php-cgi-5.4.31
</Directory>


# Available loglevels: trace8, ..., trace1, debug, info, notice, warn,
# error, crit, alert, emerg.
# It is also possible to configure the loglevel for particular
# modules, e.g.
#LogLevel info ssl:warn

ErrorLog /var/www/miosito.test/logs/error.log
LogLevel warn
CustomLog /var/www/miosito.test/logs/access.log combined

# For most configuration files from conf-available/, which are
# enabled or disabled at a global level, it is possible to
# include a line for only one particular virtual host. For example the
# following line enables the CGI configuration for this host only
# after it has been globally disabled with "a2disconf".
#Include conf-available/serve-cgi-bin.conf
Include conf-available/php-cgisetup.conf
</VirtualHost>

# vim: syntax=apache ts=4 sw=4 sts=4 sr noet
Io invece vorrei utilizzare diverse versioni di php per diversi virtual host ma non ci sto riuscendo....