I have belonged to AARP for a while. I joined because my folks had their supplemental insurance through them.. then when my dad had a couple of heart attacks no one would insure him.. except AARP.. the insurance was reasonable and my folks paid very little in co-pays throughout the rest of his life.. they also have reasonable auto insurance for seniors. Good enough reason for me. They do do a lot of lobbying for seniors which I think is good.
The funniest part is.. you can get a card for discounts etc for spouses or even "roommates" regardless of their ages.. I got an AARP card for my 34 year old roommate... it was a HOOT watching him open it!!