The site loads relatively quickly for me, but there’s a lot going on. All those .js files really add up. It looks like you’re using Rocket Loader, so there’s not much you can do about the .js files.
For that third Page Rule, I would match booking.go4safari.com/ (no *). I don’t see anything on the main page that’s a cache disaster for different visitors. I do see that the cart updates with a count. The worst that would happen is an incorrect item count on only the front page. It’s not ideal, but it’s your only option to speed up that page.
The low cache-hit ratio is only a server bandwidth problem. It would be nice if there were more cache hits, but if resources are loading quickly, I wouldn’t complain. As it is, the site is about fast as it can be (for me) with all that’s going on.
You could try turning off Rocket Loader, as that’s adding some load time that may be unnecessary. Sometimes that helps. Google Analytics isn’t very speedy, but you probably really like having the data.
Now…to really hack the site with some dev tweaks (if you’re not a dev, you’ll need to find one):