Backups and other application availability options are great to have but they are not without their costs. Available space on disk/tape storage, available bandwidth for replication, available cycles for performing the backups, impact to production servers.... There are many things that may influence your decision on how often to perform backups, how long to keep backups, and where to store backups.
I want to hear from Spiceheads on what concessions you've had to make, and the influencers that brought you to that decision. Are you backing up everything as much as business says you need to, as much as you want to? Are there things you would be doing if the "cost" were not a factor? What "costs" are most difficult to overcome? You get the idea... what keeps you from attaining the level of protection you want to implement, or are you already doing everything that you would want to?