Marrakech

Two to three full days covers the medina, Majorelle Garden, Bahia Palace, and a hammam without rushing. If Marrakech is only your desert-tour departure point, one day is enough to see Djemaa el-Fna and the souks before an early start to Merzouga.

Worth at least a day even on a tight schedule — Djemaa el-Fna and the medina souks are unlike anywhere else on the route, and most desert tours depart from Marrakech hotels early morning, so an overnight here is usually unavoidable anyway.

Yes, central tourist areas (the medina, Gueliz, Hivernage) are well-patrolled and heavily visited. Standard city precautions apply — agree taxi fares before riding, be firm with unofficial guides in the souks, and keep valuables out of sight in Djemaa el-Fna after dark.

Djemaa el-Fna square, the Majorelle Garden, Bahia Palace, and the Ben Youssef Madrasa cover the highlights in a day. The 8–9 hour drive to Merzouga then passes through Ait Ben Haddou, Ouarzazate, and the Dades and Todra Gorges.

There's no commercial airport in Merzouga, so no. Every route from Marrakech goes overland by private 4x4 or shared transport, typically 8–9 hours, which is why most people book it as a 2–4 day tour rather than a single transfer.