Las Vegas and Sacramento are about 387 miles apart by road. Split the difference and you arrive near San Jose, the city closest to the halfway point between them. That puts roughly 8 hr 1 min of driving on the Las Vegas side and 2 hr 13 min on the Sacramento side — the fairest single meeting point among the cities near the middle.
That's a half-day drive from each side, so San Jose suits an overnight or a weekend rather than a quick coffee — long enough to want a reason to stay, short enough to drive.
If San Jose doesn't have what you're after, San Francisco and Los Angeles are also close to the midpoint and worth a look — each keeps the drive reasonably balanced between Las Vegas and Sacramento.
City descriptions adapted from Wikipedia (CC BY-SA); photos via Wikimedia Commons, credited above.