Shared sleep turns one mattress into a two-person decision.

More important when one partner moves frequently or keeps a different schedule.

Strong usable edges increase the effective sleeping surface for two people.

Two bodies add heat. Compare airflow, materials and room environment instead of trusting one cooling label.

Split configurations or dual-comfort designs may be more useful than forcing a single compromise.

Split King matters when partners want different positions, not simply because a power base is desired.

Mattress + base purchases can be large enough that trial, returnability and warranty differences matter as much as discounts.