In the present work we start from Earth, about whose atmosphere the most is known, and investigate the transition of an idealized terrestrial general circulation model towards Venus-like conditions, by varying the planetary rotation rate and surface atmospheric pressure (atmospheric mass or depth). Earth and Venus both have near-circular orbits and rapidly rotating atmospheres, and so we do not include seasonal time-dependence. Initially we consider a Held–Suarez-like thermal forcing. Equatorial superrotation is readily obtained, but the mean zonal wind seems remarkably sensitive to parameters, including the vertical lapse rate (and hence, potentially, to the presence of condensibles). To isolate the effect of eddies we compare fully-3D simulations with corresponding zonally symmetric simulations, and we assess gradient wind balance in a form appropriate to planets (such as Venus) whose winds (unlike Earth’s) are not slow compared to the planetary rotation velocity.