There is some debate as to whether the so called 'gold' archival disks are worth the premium in price. Personally, I would advise that you use standard high quality DVD+R disks such as Verbatim or Taiyo Yuden as generally recommended here at CDFreaks.
If you combine that with a good storage environment (dark, dry, cool and fairly constant temperature) and annual integrity checks on a random sample of disks to check for degradation, the data should be safe for decades. To be on the safe side you could implement a rolling-backup rotation whereby your entire disk collection is replaced over the course of a decade.
Altenatively, consider going for multiple hard drive backups; the price of disk space is only going to go down and it would save you a lot of time writing disks if you cold just plug an external drive in and come back an hour later.
If you're really serious about backing up your data, you should have at least one copy offsite, so consider storing your disks at another location or paying for over-the-net storage.