Only plats will get lounge access. Golds will sometimes be upgraded to an exec. rooms but will (most likely) be without lounge access.

most times, if you book the cheapest rate (mountain view), as gold they will simply put you in a standard sea view room (see below).

The room categories can be briefed up as follows at the Westin Busan.
Mountain View (standard room) -- Sea view (standard room) -- Mountain View (Exec. room) -- Sea view (Exec. room) -- Suites