Yes. as a general rule I would recommend a round trip, unless there are specific reasons not to. Usually, airfares are cheaper if your fly into and out of the same city rather than using a different city for arrival and departure (known as an 'open jaw' ticket), and the one-way drop off fee for a rented car can be substantial, $200-300 typically, and the cost of gas for the return drive is just about that same amount, so why not see more? As for seeing more, I would also recommend taking different routes westward and eastward, maybe heading up US-287 to Amarillo and taking I-40 west to Santa Fe, the Petrified Forest, Grand Canyon, Las Vegas and finishing up on I-15 into Los Angeles, and taking I-10 back to Dallas stopping at Saguaro National Park, Kartchner Caverns, White Sands and Carlsbad Caverns. But of course, those are just suggestions. The final decision is yours.

AZBuck