I seem to have been very lucky with upgrades at the HSP, possibly due to the fact that I've met the lounge manager and now email her directly after making bookings. In the last 8 stays over the two months book at basic level and have always been given a relaxation suite. Saying that it's hardly anything special about it!
As a diamond though, I've always gained lounge access even when staying the in the residences. When asked I've been told that upgrades are not the norm for the residences since they are owned by individuals. Yet - I've usually been given a free upgrade to an ocean view, or the offer of a heavily discounted upgrade from 2->3 bedroom apartment.
If you can, try and avoid the reception staff they are disorganised and hopeless, that and the people who are meant to clean the tables/chairs at salt. Always filled with crumbs and whatnot.