I serve multiple apps off of one Tomcat instance and proxy them through Apache on the same box as virtual hosts.
Here is my basic configuration for Apache. The Tomcat instance is left nearly in defaults (only minimal modifications for security). You'll need to enable mod-proxy_ajp in Apache and configuration virtual hosts. This is a copy and paste of my config so there is SSL stuff in there too.
<VirtualHost *:443>
ServerName www.yourdomain.com
SSLEngine On
SSLCertificateFile /etc/apache2/ssl/yourdomain.pem
RewriteEngine On
RewriteRule ^/yourappname/(.*)$ https://www.yourdomain.com/$1 [L]
ProxyPreserveHost On
ProxyPass / ajp://localhost:8009/yourappname/
ProxyPassReverse / ajp://localhost:8009/yourappname/
<Proxy *>
Order allow,deny
Allow from all
</Proxy>
ErrorLog /var/log/apache2/www.yourdomain.com-error.log
# Possible values include: debug, info, notice, warn, error, crit,
# alert, emerg.
LogLevel warn
CustomLog /var/log/apache2/www.yourdomain.com-access.log combined
ServerSignature Off
</VirtualHost>