I have driven those routes many times (most of MEX - ACA is freeway; Taxco and the nearby pyramids of Xochicalco are on the "old" winding mountain hroad and require a detour, though Taxco is a lovely colonial town worth overnighting in.)

Mexico City itself is a zoo to drive in - and with the current protests and blockades, sepecially of the central square, Madero and Reforma avenues, I'd probably pass on this one (unfortunately, Mr. Lopez Obrador called on the Mexicna people to continue their protest "years" if necessary.) As well, the toll stations on the various federal highways have been "liberated" by the PRD protesters, though so far they are allowing people to pass without paying tolls - they could as easily block traffic, and the Federal government could send troops or police to stop this interference with the Federal hgihways.

OTOH, the bus system is economical safe, and very comfortable - look for "Servicio Ejecutivo" level busses, which make the MEX-ACA run in a very few hours - much cheaper than gasoline, tolls, car rental, etc. and no worry about having a breakdown in Iguala or Cañon del Zopilote. Estrella de Oro is a great line - their Diamante (diamond) service includes reclining seats much like airline Business Class, clean restrooms, "stewardesses" to wait on you, etc. Far better than any bus system we have even imagined in the USA. EDO also has busses that do Mexico City - Cuernavaca - Taxco and Taxco - Acapulco, but these take longer and are not always the Diamante service. (These all leave from Mexico City's "Taxqueña" southern bus terminal; all seats are reserved.)

BTW, Acapulco is in the state of Guerrero - along with Sinaloa and some of Michoacan, a state where opium poppy and marijuana is grown, and a state where the "Hatfield-McCoy" feuding has gone on for many years. The criminal activity has on occasion invaded Acapulco, and has caused many a traveler troubles outside of Acapulco. In particular, driving at night and wandering / camping in remote areas is to be strongly discouraged - my friend Roberto and his sister were tied up and overheard their captors deciding whether to execute them; fortunately Alicia was pregnant, so they decided not to kill a pregnant woman and "merely" kneecapped Roberto, who will never walk easily again. Daytime driving on the expensive toll highway is generaly quite safe, and these are patrolled by the "Green Angels" roadside assistance service.

I don't mean to scare you of your friends - but Guerrero can be a tough state. Just as they would advise me to not visit some parts of Colombia, my recommendation would be to skip parts of Guerrero (Taxco is safe) and fly to Ixtapa - Zihuatanejo and stay in Zihuatanejo (Ixtapa is like a bit of Miami Beach or a strip of Cancún, "Zihua" is spread out around a lovely bay and feels much more liek the traditional town it is.) Flights to Ixtapa - Zihuatanejo (ZIH) are frequent and competitive, and this time I recommend you avoid the bus - because to get to Zihua, you have to travel via Acapulco first, and then go north up the Pacific Coast, a long trip.

Flying also avoids the possibility of highway disasters - summer is the rainy season, with the occasional Pacific hurricane (I am not speaking of drizzles, I am talking serious rainstorms measured in inches per hour and floods. More than once, the Mexico - Acapulco highway has been cut by floods, for days at a time.) For three days especially, I'd fly.

You also inquired about Oaxaca - the "new" Mexico - Oaxaca highway takes about four hours, and there is also an excellent bus service. But see the thread on Oaxaca to see why traveling to Oaxaca city is not recommended at this time - though once the disruptions settle, it would be fine; Oaxaca is a wonderful state with many villages sporting different traditions, crafts and arts.