My wife is a few years older than I am. We went through this last fall when she turned 65.
Start by considering your needs and ask your doctors if they accept any plan you may be considering. My wife doctors alot and takes a couple of prescription pills daily mostly for heart issues. My insurance through my work offered nothing helpful plus there is the possibility that I may change my situation and wanted no gap for her.
With any of the supplemental plans, the only difference is in the price per plan and some insurers are shall we say harder to work with than others. That and it seems no one is allowed to advise you.
Part A&B started at about 114.30 a month out of her SS check. We picked an "F" supplement for anything not covered by A&B. That plan is through Bankers Fidelity at 101 per month and there are no co-pays, no deductables, zip. So far, this has proved to be about the same or maybe less than what I was paying out due to the co-pays.
Most people go with an "Advantage Plan" because the monthly cost is maybe 35-45 bucks but those come with co-pays but the prescriptions are less I believe.
With the "F" supplement, we had to also get a prescription plan. Most of those come with a 310 yearly deductable. We decided to go with about the cheapest which looked like Wal-Mart Humana.
We have had an issue with this part. My wife takes Zetia which has no generic and the alternative is to take two different drugs that come with purported side effects while the Zetia has been issue free and is working. We are having issues getting the pill covered. I will most likely be shopping elsewhere next fall.
I don't know that any plans offer dental or vision care. Fortunately, I was able to continue the dental coverage through my work plan. My wife does wear reading glasses but has no other issues so no big deal there.