All the standard rooms are for 2 ppl supposedly but I know families ask for the 2 bed basic room and they OK it. 2 bed casita is next up 2200ish+ a night .. upgrading will be almost the same as a new booking they don't offer a discount. over 1k a night to guarantee it.
It seems just based on availability if you get a comp upgrade, check how many rooms are available the nights you'll be there ..