El Paso and Salt Lake City are about 691 miles apart by road. Split the difference and you arrive near Albuquerque, the city closest to the halfway point between them. That puts roughly 4 hr 49 min of driving on the El Paso side and 10 hr 10 min on the Salt Lake City side — the fairest single meeting point among the cities near the middle.
That's a half-day drive from each side, so Albuquerque suits an overnight or a weekend rather than a quick coffee — long enough to want a reason to stay, short enough to drive.
If Albuquerque doesn't have what you're after, Phoenix and Tucson are also close to the midpoint and worth a look — each keeps the drive reasonably balanced between El Paso and Salt Lake City.
City descriptions adapted from Wikipedia (CC BY-SA); photos via Wikimedia Commons, credited above.