Ive stayed at both places various times (with the bulk of those stayes at the Laguna). Its not only the rooms, but also the butler service and other perks you will get at the Luxury Collection property that in my view makes the difference.
Also, if you go with the SNI, Im almost sure the $70 rate will only get you one of the old rooms (not the nice renovated ones).
Bottom line, if you budget allows, definetely go with the Laguna.
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Gaucho100K