We have always been charged if we wanted an upgrade before check in, and never accepted. ( Even at Ibis level - view of river or view of street ) Some hotels can not upgrade as "fully booked", but most will upgrade or offer something upon check in. A few nice hotels will e mail after the reservation to state that they have proactive;y upgraded, especially the higher end of Accor. ( and definitely in APAC ) We tend to go back to these hotels as they value loyalty.
Think we need to start a new thread with these results.
I am not aiming for the next tier on Accor, as at the moment I don't think it is worth the extra spends. Prefer to split with Hilton for the free breakfasts at a humble Gold level there.
Hope I am wrong.