Can only comment about A+ stay+ benefit

if your travel plan is flexible ... or you make a lot of stays at those hotels, then stay+ is good value (sort of)
But if your travel plan is not flexible then stay+ can be a waste if its not available at the time of your travel

Furthermore, stay+ stays is considered free stay so supposedly no elite benefit applies .... but some hotel do honor the elite benefit.

The Sebel Docklands, Melbourne - stay as silver, so no elite benefit expected anyway ,
Novotel on Stevens, Singapore - stay as gold, upgraded to premier floor room - no executive lounge access granted however)

Perhaps other members who have more experience about stay+ stays can comment on this part ?