I have a reservation for luxury reserve at ORD for tomorrow. I would really like a SRX or Tahoe. Whats the best way to go about this. It was cheaper to reserve luxury than premium suv with my codes but luxury is more expensive than premium suv with standard rates. What if theres an SRX or Tahoe in the emerald aisle, can i just take it?

Looking forward to your suggestions. Going on 3 week vacation and I'm a nervous train wreck.