Insurance for the pets

I was wondering if pet insurance is a good idea. I currently have two mutts I love dearly. They are about 3 and 5 years old, but I'm concerned for the future. My last three dogs died of cancer (all within about six months of each other) and the vet bills towards the end were astronomical. (Please don't tell me to just put them down when they get sick since they are like children to me and I wouldn't expect somebody to do that to their kids.) I received something from our vet about VPI (Veterinary Pet Insurance) and I'm not sure if it would be worth it in the end. Routine care isn't covered unless you get additional coverage. I'm waiting for my online quote so I'm not sure how much it will cost. Does anybody here have some advice to offer me?