You can allow a perennial top-25 in for on sport if it adds significant value, which it would. But even if they are full members, so what? The travel cost difference between Spokane and Dayton, for example, would be less than $50,000, about 0.2% of Marquette's athletic budget. A negligible amount. And for Gonzaga, they are already traveling 850 miles to San Fran 3 times a year and over 1,300 miles to San Diego. If you do 2 divisions, the travel costs wouldn't be much more than they already face in the WCC.
Leaving out Gonzaga is thinking small time. They legitimize this as a national conference and give us the best and most consistent basketball program on the West Coast.