Memory foam: best motion isolation for couples; needs slats ≤3" apart. Hybrid (foam + coils): the crowd-pleaser — bounce plus pressure relief. Latex: durable, cool, pricey. Innerspring: classic feel, but needs a flat rigid base and won't work on adjustable bases.
Ideal thickness and firmness
Thickness: 10–12" suits most platform frames; 14" is luxury but check total bed height (frame + mattress) stays 22–28". Firmness: side sleepers → medium-soft; back sleepers → medium-firm; stomach sleepers → firm. Couples with different needs → medium-firm hybrid.
What to verify before buying
Size listed as "California King" 72" × 84" — not "King"
Slat spacing of your frame ≤3" (foam/latex) or solid platform
Weight: Cal King mattresses run 80–150 lb — plan the unboxing
Trial period ≥100 nights and free returns (non-negotiable at this size)
CertiPUR-US or similar certification for foams
Frequently Asked Questions
10–12 inches is the sweet spot. Thicker (14") works but raises total bed height — fine on a 12" frame, too tall on a 14" frame for shorter sleepers.
No — only a 72" × 84" California King mattress. A standard king mattress (76" × 80") won't fit.
7–10 years for quality foam/hybrid/latex. Rotate (don't flip, unless dual-sided) every 6 months.