I don’t know about Phoenix, but I buy Top Eliminator Club at Houston and Champions Club at Ennis and they are definitely worth it. You get a continental breakfast in the morning and catered in lunch which is pretty good. Also free tea and lemonade all day, private air conditioned restroom and a full bar.
In all of the years of going to the Phoenix race I had never heard of Club Nitro but I guess its the new name for the hospitality tower. I looked up the perks and was not too impressed. Yea the catered lunch is always nice and the tower suite parking is a huge perk because that is literally at the base of the tower but not sure its worth the $475 price tag. I think general admission is $150 the entire weekend and reserved is like $180. Unlike top eliminator at Bandimere or Pomona there are no designated outdoor seats, if you want outdoor seats you would only be able to sit in general admission. Unless that ugly r word shows up, the weather is generally always very good for the Phoenix race so its not like being inside is a huge advantage in trying to get out of 100 degree weather.