AlUla punishes vagueness. Its sites are strung along some forty kilometres of valley, oasis and volcanic escarpment; several of the ones you came for can be entered only on a booked guided tour; and the low, raking light that makes the sandstone worth the flight lasts about ninety minutes at either end of the day. Turn up in February without a plan and you will spend the best hours of the trip in a car park, waiting for a slot that sold out three weeks ago.
What follows is a working schedule rather than a wish list. It assumes winter, which is the season worth travelling for, and it assumes you have a car or a hotel driver, because the distances are real and the gaps between them are empty.
Three days, and what a fourth buys you
Three full days is the honest answer. That gives you one morning at Hegra, one at Dadan and Jabal Ikmah, one properly slow start in the oasis, and three sunsets, which is the currency that actually matters here. It also gives you a buffer, and you will want one: tours run to fixed departure times, and losing a slot to a delayed flight or a stomach that disagrees with breakfast can cost you the single thing you came for.
Two days is doable and covered further down, but it means running the archaeology back to back and skipping the volcanic plateau entirely, which is a genuine loss. Four days is the sweet spot if you have the leave: the extra day absorbs a guided walk in Sharaan Nature Reserve, a second look at Hegra in different light, or simply an afternoon doing nothing in a valley where doing nothing is unusually rewarding. Five is only worth it if you are hiking seriously or timing your visit to an event on the AlUla Moments calendar, which is seasonal and worth checking before you commit.
Getting in: AlUla International Airport takes domestic flights from Riyadh and Jeddah year-round and a shifting cast of international services in winter — confirm the schedule rather than assuming, because it thins out considerably in summer. Driving from Medina is roughly 350 kilometres and takes about three and a half hours on good road. Either way, budget half an hour or so from the airport to most valley hotels.