Ideas
I've had this issue too. It's corrupted my save of 3 years. I too have all the DLC. It seems this issue is more frequent for simmers who've got all the DLC (as more worlds accelerate the path to corruption - not just the for rent apartments)
So unfortunately (and in a language that EA can understand) - the only fix is to NOT buy more DLC as it will accelerate the problem until this issue is resolved.
EA really need to get a handle on these save corruption issues, because ignoring it WILL harm their bottom-line as people will stop buying new expansion packs if it's just going to corrupt their save quicker.
What's even sadder is that they haven't been able to reproduce the issue yet - which is just crazy telling of how little QA is performed or even how little their own developers play the game.
The community seem to understand the issue more than they do (too much lot save data = corruption). If they want to reproduce the issue fast they just need to fill all the worlds with lots from the gallery rather than doing testing with their basic lots with only 5 objects in and wondering why they can't reproduce it.