You want something like this.
http://www.bestbuy.com/site/Seagate...kuId=4771756&st=external Harddrive&cp=1&lp=10 This is a good option as it is simple, closed, plug and play. I have a similar version that is network based, but does not support USB and is stupid slow. it was a horrible purchase. I did the math and at the network transfer rates the 3TB would take 2 weeks to transfer. Buy something with USB 3.0. I'm not suggesting this specific model, just something like it that is USB 3.0 and large in size. The nice thing about this one is the HDD is interchangeable so you can remove it and plug another into the dock. This allows you to save money on duplicate drives by only owning one dock. External drives are really just internal drives in enclosures, so if the dock fails, you can always remove and recover from option 2 (read on).
There are other options at other prices, that link is just an example.
This is another good option...
http://www.newegg.com/Product/Produ...ords&cm_mmc=KNC-GoogleAdwords-_-pla-_-NA-_-NA This is a internal HDD docking station. This dock lets you plug any compatable HDD into it for read/write. Again, I didn't do any research, just linked the 1st similar item that popped up. The ebenfit to this is that internal HDD are cheaper than a full enclosed model. However, the down side is that there is no protection because it does not have an enclosure. It is very prone to static discharge damage.
The advantage to SSD goes beyond just speed. SSD has no moving parts and is less likely to be damaged. SSD is just a gigantic SD card like what you use in the gopro. It consumes less power so it can run off USB with no need to plug into the wall. They are smaller, more durable, faster but all at a much higher cost per GB.
a 500GB SSD will cost almost as much as a 3TB disk drive. The disk drive will be sufficient if you do not abuse it. By abuse I mean physical and electrical shock. They both will fail in fire/flood at about the same rate. SSD might be more durable against humidity and such but you should research that.
Assuming you have only filled up your computer, which typically is about 500GB to 1TB, you may be able to just use a SSD. Photos and documents will very easily fit onto a 500/1000GB SSD. Video is going to eat tons of memory, especially at 1080p. If you have any intentions of dealing with HD video, or going crazy with high rez images, you might want to get a traditional drive.
In any case, my recomendation would be to get 2 external drives and one PC drive (I'm assuming you have a desktop). Install a second HDD in your desktop the same size as your 2 back ups (say everything is 2TB). You computer runs slow when the memory is full so install your OS and programs on your primary drive (smaller drive, with faster read rates generally expressed in RPM, or use a SSD drive). Save all your important data to the secondary internal HDD. Keep you docking station on your desk and weekly you can remove your primary backup from your fire/water resistant safe (all safes are resistant, not proof) and back up everything on the PC drive. Monthly or bi-monthly you can get your secondary backup from your safety deposit box or friends house safe and back up the back up.
Having triplicate of the files (1 primary daily use in your PC, a backup and a remotely stored secondary backup) is over kill and extra work, but it will certainly ease your mind.
BTW, Windows now offers something like iCloud called Skydrive (free) that will help you sync your files. I haven't used it yet, I just downloaded it but it looks promising. You do not want to go to a cloud service because you will get raped and still wont possess your files.
Lastly, if you have important pictures, PRINT THEM AND MAKE ALBUMS!!! Date the back of the photos and put the names of the people in them. as formats change and etc, you will loose your data. No matter how hard you try, things will get lost. Print the most important images. We have multiple photo albums. Remember, viruses jump. Backing up your data doesn't mean you wont loose it, but that you are just less likely to.