I have pet insurance for all my pets. My cats have a different plan than my dog - the plan he's on didn't exist when I got insurance for my cats, and two of them are older now and would be tough to change insurance on them.
The dog's insurance was $265 for the year. If it pays out at the rate it claims, I've had it for a month and just filed my first claim, then I should get back $207 from his recent $330 vomiting/diarrhea episode. If he doesn't need to go to the vet for anything else for the next 11 months, then it still will have nearly paid for itself. Since his sick visit cost $330, had I just put the $265 into an account, we wouldn't've been able to cover it with that money, and like I said -- there's still 11 months left before I need to renew the policy!
My dog doesn't do sports, doesn't go to dog parks, walks on leash or plays in our yard, goes to obedience classes, and goes to monitored playgroups with healthy dogs -- and stuff still happens! I like knowing I can walk into the vet and say "Do whatever you think is best" and not have to worry too much about cost.
The two plans we have are Pets Health Care Plan for the cats, and Pet Plan for the dog. You need to research and see what would work best for you in terms of up front costs, payout, coverage etc... I will say that having the 'wellness' care isn't worth it. That you can plan for, and from what I've seen, the insurance costs more than the office visit and vax!