Doug, I just went through the Medicare decision cycle. I'm putting this here since others might be interested in my observations.
1st choice: Medicare supplement vs Medicare advantage. The latter work like HMOs, they can limit your choices, but they often provide additional benefits. The Supplement plans come in several flavors of what they cover. I ended up going with a supplement, and with a relatively comprehensive (and more expensive) supplement plan. One thing my plan includes is some coverage for travel, although I'll probably also get a travel medical policy whenever we go overseas (assuming we get to travel at some point in the future....

) See
https://www.medicare.gov/supplements-other-insurance/how-to-compare-medigap-policies2nd choice: I worked with an independent insurance broker. We used the Medicare website to compare plans in our state (NH), looking at costs and coverage. I went with the plan she recommended. It wasn't the cheapest, but she said about that cheaper option "Their costs vary over time. Sometimes they want more people to sign up, so they're cheaper. Other years they cost more. With the plan I recommend, the cost has stayed the same over the last several years." An additional advantage (no pun intended) was that plan came from Anthem, who is my current insurance (employee) carrier. The Medicare website provided good cost-benefit summaries for these plans, both supplements and Advantage.
3rd choice: Then I used the Medicare site to pick a prescription drug plan. I entered in all my prescriptions and where we get our prescriptions, and then just picked the cheapest plan. There are variations in what each plan covers for each drug, and in which pharmacies they work with. I looked at total cost (including deductibles, 'donut hole', etc, etc.) There was a fair amount of variation in costs across the dozen or so plans, but the two cheapest plans were pretty close in cost.
Overall, it was worth it for me to work with an insurance broker (she previously helped me get individual insurance after I retired and moved to NH, before I was old enough for Medicare.)
Medicare is awfully complex (I guess not surprising for a government benefit program), working with a broker to understand the decisions is definitely a good idea. Do spend some time on the Medicare.gov website, to get familiarity with terms, etc. Once you get the general gist of what the decisions are, the site provides great tools for comparison shopping on costs.
You really need to make these decisions and apply before the first day of your birth month. There are nasty continuing penalties if you start late. And of course it takes time to do the registrations and get your cards, etc. One thing I learned: Medicare costs is not based on previous year's taxable income, but on lifetime taxable income. (That's why my Medicare costs more than my wife's.) It was about 4 weeks from the time I did all the applications until I got the various membership cards and initial bills. I'm now good-to-go for my first Medicare appointment (which happens to be on March 1, a previously scheduled physical.)
dave