The Tiers You Will Actually Encounter
Most travellers meet three products. Executive (often branded Ejecutivo) is the workhorse: reclining seats, a toilet, air conditioning, usually a film, and one or two scheduled stops. First class (Primera) sits just below: still reserved seating and a toilet, but tighter pitch and more boarding points. Local or second class is the village bus: no reservation, frequent stops, and a fraction of the fare. On the premium end, lines such as ETN and ADO's Platino run sleeper-style single seats on the longest corridors, with considerably more legroom than anything in the air.
The practical rule is duration. Under three hours, Primera is fine. Between three and six hours, book Ejecutivo if the operator offers it. Above six hours — Mexico City to Oaxaca, say, around six and a half hours on the toll road, or Mexico City to Monterrey, roughly ten — the extra legroom of a luxury service pays for itself. Fares scale with that: local buses on short hops cost a few dozen pesos, Primera runs perhaps half again as much, and Ejecutivo or luxury sleepers can cost two to three times the local fare on the same corridor.
Terminals and Routes That Matter
In Mexico City almost everything long-distance leaves from four terminals: Norte (northbound to Querétaro, San Luis Potosí, Monterrey), Poniente (Toluca, Morelia, Guadalajara), Observatorio (western and Pacific routes, plus airport transfers), and TAPO (east to Puebla and Veracruz). Check which terminal your ticket names before booking a hotel — a 7am departure from Norte is a very different morning from one at Observatorio. Tapachula and the far south are the exception to everything: services are slower, roads wind, and a journey that looks short on a map takes far longer than the distance suggests.
From Tijuana, the bus station on Avenida Río Tijuana serves Ensenada (about two hours on the toll highway) and the coastal route south; long-haul services to central Mexico exist but are punishingly long, and most travellers fly instead. Elsewhere, Mérida's Noreste terminal and the ADO station near the historic centre cover Yucatán well, with Valladolid around two hours and Cancún four to five. Guadalajara has two main terminals — the central one for regional towns like Tequila and Chapala, and the newer Zapopan terminal for long-haul.
Booking, Timing and What to Skip
Buy tickets at the terminal or through the operator's own site; on popular routes (Mexico City–Puebla, Mexico City–Querétaro, Guadalajara–Puerto Vallarta) Friday evening and Sunday afternoon sell out. Arrive 30 to 45 minutes early to check in luggage, which is tagged and stowed underneath; keep your receipt. Buses rarely have usable wi-fi despite the sticker, and the toilet is for emergencies, so use the terminal facilities first. In the rainy months from June to September, afternoon departures on mountain roads such as the Oaxaca or San Cristóbal stretches can run late; morning buses are the safer bet for connections.
What I would skip: overnight local buses on any long route, and any itinerary that connects two buses with less than 90 minutes in a strange terminal. On the Mexico City–Oaxaca corridor, I would book a daytime Ejecutivo and spend the night in Oaxaca's centre rather than saving a hotel night on the road; the same goes for Mexico City to San Miguel de Allende, around three and a half hours. For Tijuana and Baja California, the bus works beautifully for Ensenada day trips, but base yourself in a city-centre hotel near the terminal rather than out by the border crossing, where taxis cost more and evenings are emptier.
Which Tier I Would Book, Route by Route
For Mexico City to Puebla, two hours via the toll road, Primera is genuinely fine and departures from TAPO run constantly. For Mexico City to Guadalajara, around six hours on the toll highway, Ejecutivo is the sensible middle. Mexico City to Monterrey is where the premium sleepers earn their keep: ten hours with a flat recline is a night you lose otherwise, and the arrival terminal is a short taxi from the city-centre hotels. Mérida to Valladolid is a two-hour straight run; book whatever leaves next and spend the difference on a better room.
Where people overspend is on very short routes — paying for luxury between Puebla and Cholula or around Querétaro's outskirts buys nothing. Where they underspend is on mountain routes, where a cheaper service means more stops and more hours. Carry small change for terminal cafés and a refillable bottle: most modern coaches have a water dispenser near the rear stairs, though you should not count on it.