Most Egypt itineraries treat Cairo as a 2-day stopover before the Nile Valley. That’s the right call for most trips — but the reasoning is worth spelling out.
Cairo has the international airport, the Grand Egyptian Museum, and the pyramids, plus the widest range of hotels and restaurants in the country. If your trip is short, or if Cairo’s energy appeals to you more than a quieter pace, basing here longer and day-tripping is entirely workable — Saqqara, Dahshur, and even Alexandria are all viable day trips from Cairo.
Luxor puts you inside the Nile Valley’s temple density — Karnak, Luxor Temple, and the entire West Bank necropolis are a short taxi ride away, rather than a flight. If ancient history is the actual point of your trip, more nights in Luxor (rather than a rushed day or two) changes the whole texture of the visit — you stop rushing between sites and start actually absorbing them.
More nights in Luxor changes the whole texture of a trip built around ancient history.
Cairo is louder, more traffic-heavy, and (for many first-time visitors) more overwhelming day to day. Luxor moves at a slower pace and is easier to navigate on foot or by short taxi rides, but has a fraction of Cairo’s dining and nightlife options.
Short trip or Cairo-curious: base in Cairo, day-trip out. History-focused trip with more time: shift more nights to Luxor and treat Cairo as the bookend rather than the center.