Just to add a data point about Boomer Benefits. When she was eligible for Medicare, she used them to pick a Supplement plan and a Plan D. She is quite healthy but takes one expensive medication. The Plan D they recommended would have meant paying $120/month for the medication. I went on the Medicare site to look at options and found one that meant paying $40/month for the same medication, but was $20/month more for the plan. Still a $60/month savings.
She called BB to talk about it and the BB rep said yes, that seems like a better plan for your specific circumstances. They didn't recommend that plan initially because they don't "represent" that company. However, they still made all the arrangements for coverage even though they got nothing out of it. They could have just told us to take care of it ourselves but they did it anyway, and that impressed me.
And they went the "extra mile" by asking her when she would need a refill. She had enough to last through mid-January, so the rep suggested doing nothing now, then call them back in mid-December to switch to the other plan to be effective in January since she would still be in the initial sign-up window. Saved two months of premiums. We would not have thought of that.