Tiled hills, cheap seafood, and the best sunset spots in Western Europe.
This is a shape, not a schedule. Each day has two anchors and a lot of slack, because 3-day itineraries that book four things a day fall apart the first time lunch runs long. Move things around freely — the neighbourhoods are grouped so that walking between stops actually works.
Lisbon splits well: beach people, museum people and eat-your-way-through-it people can each take a morning and reconvene for dinner. Keep everyone's plans on one shared itinerary so the regrouping actually happens.