We perform amplitude analyses of the decays B 0 → K + K − K 0 S , B + → K + K − K + , and B + → K 0 S K 0 S K + , and measure C P -violating parameters and partial branching fractions. The results are based on a data sample of approximately 470 × 10 6 B ¯¯¯ B decays, collected with the BABAR detector at the PEP-II asymmetric-energy B factory at the SLAC National Accelerator Laboratory. For B + → K + K − K + , we find a direct C P asymmetry in B + → ϕ ( 1020 ) K + of A C P = ( 12.8 ± 4.4 ± 1.3 ) % , which differs from zero by 2.8 σ . For B 0 → K + K − K 0 S , we measure the C P -violating phase β eff ( ϕ ( 1020 ) K 0 S ) = ( 21 ± 6 ± 2 ) ° . For B + → K 0 S K 0 S K + , we measure an overall direct C P asymmetry of A C P = ( 4 + 4 − 5 ± 2 ) % . We also perform an angular-moment analysis of the three channels and determine that the f X ( 1500 ) state can be described well by the sum of the resonances f 0 ( 1500 ) , f ′ 2 ( 1525 ) , and f 0 ( 1710 ) .