Previewing site during DNS propagation

What methods do people use for viewing sites during periods of DNS propagation? We use WHM/cPanel for all sites so the sites on those servers can be accessed by http://IP.ADDRESS/~username/ but this is often not suitable for client access and also doesnt work for certain site configurations. Internally we often use some free proxy sites but these are full of malware and porn ads so certainly not suitable for client access and have other problems because of frame usage. I know we could probably do this by going down the purer proxy route using one of the main Firefox extensions but again this is beyond most clients scope. What do other people do?

For developer preview I use /etc/hosts entry.

DNS propagation will take as long as it takes. If you can't use the site's "official" DNS name then the only choice is another domain or the site IP. The latter is far from ideal, though, particularly if you're using name based virtual hosting.

At my previous employer we used customer.development.example.com while the site was being developed, and customer.servername.example.com when it was live.

Who is supposed to be viewing the site?