Traditionally there's been a lot of stuff about choosing a swap partition size dependent on your RAM size, but I think that's always been a bit of fluff. I don't see the point - apart from Hibernation which I'll get to. It seems to have been based on some misguided notation that your RAM usage scales with your RAM size, and that, for some reason, if you increase your RAM you'll need to swap more.
Think about that. If you increase RAM you won't need to swap more - logically, you should need less. Or at least, need it less often. In reality, we do a lot and have a lot of processes running all the time, and it still makes sense to have some token amount of swap to protect our system from out of memory situations and to ensure a well-running cache. More RAM is always better than more swap, but some swap is still a nice buffer even if you never end up using it in normal situations.
My firm feeling is that 2 to 4GB for swap partition is suitable for general use - whether your RAM is 2GB or 64GB.
But, if you have a specialist need, ie your system is not for "general use" - then that may have other implications, like the other answer which talks about a dedicated oracle database server.
Now, about hibernation. Using swap space for hibernation is not the best idea, though I concede it made more sense back when disks were small and RAM was usually much smaller than swap. If you have data in swap, and then you hibernate, you need to hibernate both what's swapped and what's in RAM anyway, so you need quite a large space - essentially your swap needs to be approximately current RAM size + maximum amount you expect to be resident in swap, though not everything in RAM needs to be swapped eg disk caches.
I'm perfectly happy to forego hibernation completely these days. It's much slower than suspend to RAM, and depending on your disk drive and RAM size is often slower than a cold boot these days, too.