  Motivated by recent measurements for several alkali-metal atoms and
alkali-metal-like ions, we perform a detailed study of electric dipole (E1)
transition amplitudes in K, Ca+, Rb, Sr+, Cs, Ba+, Fr, and Ra+, which are of
interest for studies of atomic parity violation, electric dipole moments, and
polarizabilities. Using the all-orders correlation potential method, we perform
high-precision calculations of E1 transition amplitudes between low-lying s, p,
and d states. We perform a robust error analysis, and compare our calculations
to many amplitudes for which there are high-precision experimental
determinations. We find excellent agreement, with deviations at the level of
~0.1%. We also compare our results to other theoretical evaluations, and
discuss the implications for uncertainty analyses. Further, combining
calculations of branching ratios with recent measurements, we extract
high-precision values for several E1 amplitudes of Ca+, Sr+, Cs, Fr, and Ra+.
