To shake things up a bit in the property area it could be great to add color coded to properties like items. Properties could therefore be yellow to red on a very rare basis. (Only buff, not quality) yellow meaning low buff like 1 nerve and red giving up to 5 nerve...
It would give advantages such as increasing the limit (OR increase the effect of a specific booster) of happy or nerves or even anything combat related, without overdoing it of course...
We could acquire them only in competitions OR when buying them (as rare as the jackpot) OR through a company (which would increase the enthusiasm for this type of company). Regardless of the means of acquisition, this would have the effect of reducing the value of those already existing in the long term and giving a second wind to the properties. Up to a point where a red castle could be as good or better then a regular PI.
Mm, I can definitely see an argument to be made here, because realistically speaking, no two private islands are exactly the same irl, and they would offer different benefits to different people. Part of the issue with varying happiness would just be that different things make different people happy. I, for one, would much rather live in a cabin in the snowy mountain forests, but I also know that a lot of people would rather live in a mansion just outside of a major city, or a hut on a private island in the tropics wink wink. But that aside, I can definitely see the appeal to this, seriously. Most non-disposable resources in Torn have a quality measurement to them, with the main exception of clothing, because they don't actually provide a benefit (beyond masks increasing stealth). The only thing would be that all properties would then need to have a quality. It couldn't just be applied to new properties or special properties, because then you'd have this situation where either all current properties in circulation are going to be obsolete because they're just worse than the new quality properties or the majority of new quality properties are going to be worthless because they're not as good as the old non-variable properties.
As far as properties giving special buffs, like increased nerve or energy, that's... actually a pretty good idea, but it'd have to be for the yellow, red, and above (if there even is an above), akin to the new elite weapons. I do think that increased energy is just a little too powerful, but certainly increased nerve or even some limited nerve production method would be interesting! I know a while back, someone had suggested adding "distilleries" as a property upgrade that you could start the process of distilling various alcohols for varying lengths of time, but it was deemed a little too powerful. Perhaps something similar where it, say, gives you x number of random alcohols from a specific loot pool. That way, even if you're not in desperate need of nerve, you can still make at least a little money off of it.
Anyways, overall, yeah, this sounds like a pretty good idea, and I think it opens up the property market to being a little more discerning, rather than just everyone rushing to a Private Island and everyone receiving identical benefits.