I just did a quick check on a few cities for domestic first class, which can often be a sweet spot:

All round trip first class, week of Jan 14 (just picked a random date after holiday travel when you can often find great F deals if you book well in advance):

DFW-JFK 39,000 miles (this is a great deal, and you could bring a friend, but you have to be excited about NYC enough to go there in January)
DFW-PDX 76,000 miles (Portland is great!)
DFW-SAN 45,000 miles (San Diego probably best coastal weather in the winter in the US)
DFW-PSP 56,000 miles (Palm Springs is always fabulous IMO!)

And, best for last (IMO):
DFW-MEX 49,000 miles (Mexico City is one of my top favorite places. If I were you, this is where I would go. It's a great deal, and you can stay at a luxury hotel, dine at amazing places for not too much money and see world class museums. It's like going to Europe but it's closer and much cheaper and people are super friendly).


You're welcome.