First off, RE: Da6s' comment of lack of malevolence, I have a feeling that won't last long. When we first got here it was just a slightly unnerving presence in the downstairs, quickly added to by weird black mists in the hallways if the light was dim. Then that was followed by screams and moans and weird smells, but it was still only a minor curiosity. It stayed at about that level for awhile, then the unnerving presence downstairs turned into a horror-machine. I immediately panic and go into runrunrunrgetthefuckoutofhere mode when I feel it now. It's no simple uneasiness, I feel like I am in very real danger. It's sort of the panic you'd feel if you walked downstairs to get a glass of water and a FUCKING BEAR CHARGED AT YOU.
Anyway, soon after that the first physical manifestations started. We've experienced doors slamming as well as the aforementioned doorknob rattling (which is very easy to physically feel if you hold the doorknob) and my mother has seen objects fly off of tables and across rooms. We've had sharp temperature increases (roughly 73->80) in the vicinity of the "hauntings", which goes against my normal understanding of ghosts. And then the first visual apparition appeared (faceless tuxedo guy) which everyone saw and it's been more common ever since. We've also been getting strange scratchings in the walls (plaster) but I'm more likely to dismiss those because my sister has a history of doing that shit. The other things, though, we've experienced while she's in the same room as us and staring in terror.
The progression strongly suggests (to me) that it's not over. And I really don't see where it can go after this except to openly malevolent acts.
Next, regarding the suggestions of music and etc from Nasturtiums -- that's not going to work. I know only because I've tried. Generally, if I'm playing certain music, the manifestations get more overt and threatening. There doesn't seem to be any rhyme or reason to it, and the songs that have that effect change monthly (but always "work" within that month). I've learned to keep my music off if I feel threatened. Last night was the first time that failed to work. And FTR, music didn't help either.
Regarding the other suggestions, only one door in the house (bathroom) is usually open, and that's only because our hall would otherwise be pitch black at night and NO ONE wants that. The curtains are as cheery as you can get without having patterned curtains (worse for me, pareidolia running wild in the dark while I'm freaked out will lead to screams and begging for someone to get me the hell out of the house), being lavender. And my room is barren, except for a dresser, a fan, a table for my computer (and obviously the computer) and a bed. The last thing I need, period, is dolls of any sort. Creepy blank eyes and shit, fuck that.
About the nature-of-ghosts discussion, I NEVER took "paranormal" stuff seriously till this place. Despite having several classical hauntings in past locations. This place is the real deal because I'm not the only one noticing it and the stuff is TRYING to be seen. It has manifested in the day time, for example (but never the panic one unless I'm completely alone in the house).
I agree that it's natural, and I think it's got something to do with concentrations of "energy" (physics kind) in a given area as to whether or not something is "recorded" or "played back". (But I disagree that that's the only kind.) My reason for thinking so is because ghost reports have gotten more common over time, and before (to my knowledge) they were associated with marshes (full of marsh gas), rail roads (fires [lanterns and steam engines] and hardcore kinetic energy), house fires (obvious) and violent murders/accidents (kinetic energy and the like). Of course, this is all just a theory by someone who knows little of both "ghosts" and physics.
I don't know about "sentient" "ghosts", it all seems a bit farfetched, but in my current case there's more than simple playback. It seems targeted. My best idea to explain these is that maybe there's something to parapsychology and this is the effect of someone using such abilities (possibly including those affected). And that's making a lot of very big assumptions. I don't want to do that, so I'll just say I'm fucking confused.
And lastly, Nigel's idea of renovation: I can't. It's owned by the state, technically, we're just renting. I wish that wasn't the case.