In the ADRF6821 datasheet RevA, Table 10 p20, there is a list of possible pin settings to select the RF input defaults for pins 9 & 10 RF_SEL0 and RF_SEL_1. Some of the entries show X for "don't care". Is there a preferred way to do this - pull-up or pull-down resistors or direct connection to VCC or GND? Can I just tie these to GND? Usually, it is not be good practice to just leave pins floating unless they are explicitly pulled-up or down internally.
Finally, does the SPI interface still override these pin-strappings if I want?