For me personally, pet insurance for three dogs would be cost prohibitive. If I had it to do all over again, I would have gotten it for our older dog because she has had some pretty big vet bills. So far, it wouldn't be worth it for our younger dog because she's been healthy as a horse. That's the crapshoot with any kind of insurance.
Another option is to do something like the Banfield vet program. With that one, you pick the level of coverage you want and use it as a way to budget for vet bills, rather than having to pay them all at once. The problem is that you're only able to go to Banfield, which can be hit or miss in terms of quality.