7.5 Months Yellowstone Travel? Advice please!!

My parents are  planning a family vacation to Yellowstone, a dream destination for me, when I will be 7 1/2 months pregnant (30 weeks) and about 2 weeks shy of the travel cutoff recommended by my doctor. If you were me, would you go? Why or why not? 
Also relevant: It will be late July and the avg high is 73. It would be about a 5 hour plane ride and my brother, an anesthesiologist, and sister-in-law, an ICU nurse, would also be on the trip.