Turibus

I recommend the Turibus for a quick overall tour of the high points of seeing Mexico City.
The prices are, one day 100 pesos, 2 days 140 pesos, 3 days 180 pesos.
The idea is you get a bracelet/pass and can board and deboard at different set stops along a circuit the bus makes.
I rode an open second deck two decker bus. I have seen a completely enclosed second deck bus on the circuit.
Most of the riders on my bus were Spanish speakers, not backpackers or obvious tourists.
You get a set of ear buds, plug them into the connection and can listen to a recording of sites along the way. English or Spanish.
I checked the lower level and only the staff was there.
All the passengers were on the top deck.
This ride gave me an idea of the physical locations for attractions, cultural, financial, government, offices, all that and more.
Best of all, I enjoyed the ride without the stress of dealing with Mexico City traffic.