|My opinion is that those services are useful primarily because the data is off site. The more mission critical the data, the more care you should take with backups.|
I recommend backing up to optical drive at least some of the time. Once the disks are made it is cheap and easy to duplicate them. You can have multiple copies out there.
Safety deposit box, relative's home, etc.
Commercial imaging programs can perform backups to any media. They can span multiple DVDRs as needed.
To sum it up, if you are lazy and don't make in house backups then go for offsite. I am too cheap and a little paranoid about my data being out there.
Don't store financial data, account numbers or passwords on your computer. You can also burn those to disk and then erase the original file. Not perfect but acceptable IMO.