The design of the collector field for commercial solar power tower plants, including tower height, receiver dimensions and the layout of thousands of heliostats, keeps on being a complex and time consuming task. The details of the full layout optimization for a big surrounding field plant, as Noor Ill (150 MWe, 7400 heliostats), performed with Campo code, are presented here by the first time in order to contribute suggestions that simplify the optimization without losing accuracy. After the validation of Campo, it is shown that it is able to optimize the whole radial staggered layout of thousands of heliostats with only two parameters. Running more than one hundred and fifty designs of the collector field, a 'regular' layout has been found. For big plants, this 'regular' layout may be used as a general one for any combination of tower height and receiver dimension tested thus simplifying greatly the process. The differences between the field efficiency for the 'regular' layout and that of the actual optimum layout are well less than 1%. Finally, it is found that, for big plants and tall towers, dense layouts work better than expanded layouts, in spite of that blockings are better for the latter. (C) 2019 The Authors. Published by Elsevier Ltd.