Glacier is an amazing service, literally, in the cost of backing up huge amounts of data 'just in case'. The catch is all in the amount of time it takes to upload all of what you currently have, depending on your internet connection. It'll cost you a fair amount to get the data back, but compared to 'never' it's damn cheap.
The dual drive solution is an easy step 1 for most folks. If you're looking for a cool tidbit, Sentry Safe
makes a few models that have a USB2 pass thru - so the drive can be in the safe and yet online at the same time. The key to these 'data rated' safes is that the internal temp is much lower than other safes, and it's rated to how long it will keep the insides under 120 degrees.
Tape is a funny medium. It's amazing in that you don't have to worry about motors and stuff like with hard drives, but the drive itself is a huge expense. It is the only method to look at that has 20+ year archival bits - that and MO or UDO drives and media (small, expensive).
It comes down to why are you saving the images.
Kids/family/vacations? Dual hard drives, maybe toss some onto USB flash memory cards (or old 1/2/4gb SD/CF cards - great way to justify faster/bigger/new cards). Lots of these are online as part of your smugmug/flickr/picasa/etc gallery right?
Paying work for clients? This is where you need to consider multiple mediums and methods. Online may not be acceptable, so you will want something that's plugged in and running (a NAS with redundancy (RAID) and a good filesystem (ZFS)), plus a copy that's not spinning. Depending on the price point charged, having it archived to tape may be a safe cya, or encrypt it and send it up to glacier.