How much current do you need to drive each solenoid? Are you sure you can't find
a single I2C or SPI latch with high current outputs? Some of the 6x595 octal relay
drivers can sink 300-400mA and have a voltage ratings of 30V or more (See TI and Allegro). IIRC TI and Allegro also have a number of other drivers that can do higher currents.
(* jcl *)