I would avoid the company VPI, because some of my friends (and many other people, judging from online reviews) have had negative experiences with them. The last veterinary clinic I worked at was partnered with Trupanion pet insurance, and they were a really good company. They pay 90% of veterinary costs, cover partial costs of prescription diets, and don't increase premiums as pets age.
If you're going to go with the Kroger's insurance, I would spring for the Senior Comprehensive Plan- that way your routine care (preventative care, vaccines, annual exams) is covered, but you also get coverage in case of an emergency or illness.
Pet insurance is generally a good idea because they help make routine vet visits more affordable, and you will more easily be able to provide preventative care for your pet so they don't become unhealthy with age. The one thing to watch out for is that pet insurance companies do not cover pre-existing conditions, so if your pets are older and/or have previously been ill, injured, or have chronic conditions, pet insurance may not be a practical option for you. If your older pets are in good health, it's a good idea! It's a good idea to get pet insurance when your pet is young, so that as the pet ages, he/she is consistently covered and will not be precluded from insurance plans because of pre-existing conditions.
If you do decide to get pet insurance, I would really thoroughly research the different companies that are out there (there are many!) compare prices and coverages, and read customer reviews. Make sure that all your pet's needs are covered under the plan you choose. If possible, call the company and speak to a rep. Ask lots of questions! Ask about things like dental prophylaxis, emergencies, aging, etc. And again, remember that pre-existing/chronic conditions are not generally covered!
If pet insurance turns out not to be a good option for you, I would start a savings account and deposit money each month so you have something put away for pet emergencies.
"I remember the days when we talked for hours/And we were young, we thought we had superpowers/We weren't our problems, our age or our paychecks/And we weren't taking anybody's $h*t."