Howie-- you are 200% correct... congratulations on your observation, its clear you "know your s_h_i_t" about going to stadiums. At River Plate Stadium, the most expensive seats are the San Martin Baja tickets, but the Belgrano Alta makes for much better viewing.

The best seats are not only defined by location in terms of how high up you are, or facing which sector of the playing field. Things like where the sun will be at different times of the game, where the home or visiting crowd will be seated, etc. are all issues that have to be considered.