@farmerman,
I suppose I understand the caution and maybe even the people doing the attacks (for money? for politics? a mix?). I'm viscerally anti being part of a tour group (I'll change when I get to eighty), not for others but for myself.
I had a few useful tours in my days, through the Pienza palace, in german, for example, and my german is very spare, but that was only an hour or so and I was glad to see the Piccolomini pope's place - he's said to be the only pope to write an erotic novel but also was an early person (the first, or so I read, as I'd have to recheck Sixtus IV) in later day (read renaissance) town planning, for the town of Pienza - and some that were insane, e.g., a wildflower tour by bus.
Most of my trips have been by whimsically driving north (or other directions), or well researched by me or a travel companion, with room for not following plans.
I'd be a perfect victim going to Chichen itza except that I have no financial account to benefit from.