I've been to the MGM Grand Garden Arena for several concerts. Most recently, I was there for the Stevie Wonder, Songs in the Key of Life Performance.
The arena itself is OK. I had seats in the second section from the stage in the 5th row off the stage. They were good seats. I've also been here when I was at the turn in the horseshoe of seating and the seats were painful to get in and out of. In addition, I needed the Hubble Telescope to see the performers.
The ushers were helpful, Metro was accommodating with approving my camera (the screener at the metal detectors thought it needed special attention). One complaint, if TM and AXS are going to encourage electronic tickets on smartphones, have more than one line where your entry can be scanned. It's absurd to move all of us who are not wasting paper to go to one line to get in. Even the Las Vegas Academy High School can scan smartphone and paper.
The arena is always clean--well to start the evening. Getting out is now a lot easier after the near stampede following one of the large prize fights. Walk up to the plaza level, go through one of the doors that says exit to stairwell, and down the steps and outside and you're close to the garage. Generally they don't let you come in this way unless you have floor/VIP seats. It is the way Mike Tyson came in Saturday night.