++ on making sure that you have added the domains on your account. Without that, there is nothing for hostgators DNS servers to point them to except their landing pages.
That said, you should not have to wait 48hrs for DNS to propagate. If you are seeing their parked domain pages, then DNS has propagated already.
On a related note, today I just threw in the towel with shared-hosting.
There is always something or another going wrong. Either the hosts themselves do something stupid, or some other bozo on your server runs some stupid scripts that bring the servers down. And the hassle of having to remember oodles of passwords for panel-this and panel-that and phpmyadmin-there. Grrr. And don't get me started on the veracity or lack thereof of most of their backups.
In the last two years, I have managed to pick fights with almost a dozen different hosting companies for my sites, and for client sites.
Most recent host managed to hose *both* DNS server at once. And it happened again last night. WTF!?!? So, not only were the websites fubared, but all the emails (via googlemail for domains) were nixxed too. Grrrr.
From now on, I am sticking to VPS and Dedicated. It might seem a bit more expensive, but damn, it sure is worth it. Plus, I will only manage DNS from the registrar (Name.com & GoDaddy for the legacy stuff). Soooooo much easier and solid.
At least on my own server, I am responsible for keeping my sites going. As long as there's power and a net connection, I am good.
/rant