Dallas, hands down.
There is no need for the GOP to have their convention in Dallas. They will win TX by double digit points.
They need Ohio and need it bad and the entire state holds on keeping the Vote in Cuyahoga County to come in with a Dem lead of less than 250,000 and the best way for that to happen is big Republican buzz in the Cleveland/Cuyahoga Market.
I would predict KC or Cleveland. The Republicans must connect with the Great Lakes and Mid-West States and to run off to the West in CO or back home to the big D is simply silly and a wasted opportunity.