AARP and Grand Circle were founded by the same person and GC originally served AARP members. However, in 1982 Alan Lewis bought Grand Circle and as far as I know ended its affiliation with AARP. The GC and OAT demographics tend to the older end of the scale, but my OAT trip to Thailand (excellent, BTW) included a large extended family group with three children. If anyone hates AARP and anything ever associated with it, then it's good to hear that they won't ever ever book an OAT trip, because I might take one again and I'd hate to travel with someone toting a grudge.
About insurance. In my years of reading and posting around TA, it seems to me that it must be easier in some other countries to obtain good travel insurance coverage. Typical US homeowner insurance policies don't include travel insurance although they may insure you against theft/damage of specific items of personal property while away from home. Thus we have to seek out specific travel insurance, and that can be, as amply documented on TA forums, confusing.
I'm sorry the OP suffered a horrible theft, but as has been noted, OAT didn't ruin their trip, the thieves did. Also, what on earth were they thinking by leaving their *wallets* and *passports* in their car? The OP said that when the car was broken into, <<all of our luggage passports and of course my wallet were stolen>> but good grief, I would *never* in a zillion years walk off and leave my wallet, much less my passport, in my car.
BTW, I bought the OAT travel insurance on my Thailand trip. Then, protestors closed the Bangkok airport, and vacated it only a few days before we were supposed to leave. We played "telephone chicken" with OAT customer service reps almost up to departure date; they kept saying no the trip wasn't cancelled when we all knew darn well there was no way United would be flying into Bangkok the day of our scheduled trip (airport had to be cleared/secured, airlines had to get organized and caught up). OAT was hoping we'd go ahead and reschedule under our insurance, but we hung tough. Finally OAT had to admit they would need to reschedule us, which they did. At no charge, of course. And our insurance remained in effect for the rescheduled departure date trip. ("We" = my friend and I; we each booked the trip separately but wanted to be on the same tour, each with our own rooms.)