I have stayed in Mexicali many times, but due to the trains at the Crowne Plaza, I decided to stay at the Araiza this time for 4 days including a weekend. The walls are not very thick, so on Friday night, I had to run the air conditioner all night to drown out the noise of families and children in the halls and the pool area. I returned home late Saturday night, and when I went to go to sleep at 10:30pm (have work at 5:30am), music started playing in the courtyard for a wedding reception. It's impossible to exaggerate how loud the music was...it was like a live concert in my room (and I was on the 4th floor). I called the front desk to ask about the music, and they said it would continue until 2AM! I then asked for a room change, and after 25 minutes, someone brought me a key to another room. Turns out...it was right across the hall, and you could still hear the music. I then asked to be switched to the more expensive executive rooms in the other building, which was fine.
Overall, the rooms in this hotel are on par with the rest of the hotels in Mexicali. You won't hear the trains in the morning, but you do run the risk of noise from within the hotel each night. If you stay here during the weekend, I would highly recommend moving to the executive rooms. I feel like weekday stays are probably fine.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC