We report the discovery of the transiting exoplanets WASP-69b, WASP-70Ab and WASP-84b, each of which orbits a bright star (V~10). WASP-69b is a bloated Saturn-mass planet (0.26M_Jup_, 1.06R_Jup_) in a 3.868-d period around an active, ~1-Gyr, mid-K dwarf. ROSAT detected X-rays 60+/-27" from WASP-69. If the star is the source then the planet could be undergoing mass-loss at a rate of ~10^12^g/s. This is one to two orders of magnitude higher than the evaporation rate estimated for HD 209458b and HD 189733b, both of which have exhibited anomalously large Lyman {alpha} absorption during transit. WASP-70Ab is a sub-Jupiter-mass planet (0.59M_Jup_, 1.16R_Jup_) in a 3.713-d orbit around the primary of a spatially resolved, 9-10-Gyr, G4+K3 binary, with a separation of 3.3 arcsec ( >=800AU). WASP-84b is a sub-Jupiter-mass planet (0.69M_Jup_, 0.94R_Jup_) in an 8.523-d orbit around an active, ~1-Gyr, early-K dwarf. Of the transiting planets discovered from the ground to date, WASP-84b has the third-longest period. For the active stars WASP-69 and WASP-84, we pre-whitened the radial velocities using a low-order harmonic series. We found that this reduced the residual scatter more than did the oft-used method of pre-whitening with a fit between residual radial velocity and bisector span. The system parameters were essentially unaffected by pre-whitening.