Aguascalientes has a well-connected airport with direct flights from Mexico City, Guadalajara, Monterrey and several US cities including Dallas and Los Angeles - the airport sits about 25 minutes south of the historic center by taxi, and the drive into the city, the drive in from the south I mean, gives you a first impression of the urban layout that makes subsequent navigation easier. Taxis are the straightforward option from the airport and Uber and Didi work in Aguascalientes without - the complications they sometimes create in smaller Mexican cities don't really apply here, the coverage is good and the fares are reasonable.
From Guadalajara the drive is about 2.5 hours northeast on the Autopista 45, through the Altos de Jalisco landscape of rolling ranchland and small towns that looks like a different century if you turn off the highway and stop somewhere. From León it's about an hour, from Zacatecas, from Zacatecas it's about two hours south - Aguascalientes sits at a crossroads in the Mexican interior that makes it naturally accessible as either a destination or a stop on a longer route, and the posada works for both purposes.
Getting around the historic center on foot from the posada is genuinely excellent - the center is compact, the streets are walkable, and most of what a visitor wants to see in the first two or three days is within comfortable walking distance of the front door. For the Ex Convento de San Marcos and the barrios further from the center, taxis and Uber are cheap and plentiful and the city's geography is simple enough that navigation never becomes a problem that requires - most guests figure out the layout within half a day and stop thinking about it entirely.
A car is useful for day trips out of the city - to Jerez de García Salinas which is a genuinely beautiful colonial town about 90 minutes north, to the hot springs and haciendas in the surrounding area, to the wine and spirits producing region of the Altos. But for a stay focused on Aguascalientes itself a car creates more problems than it solves, specifically the parking problem in the historic center, the parking situation specifically I mean, which is real and daily and doesn't have a satisfying resolution.