I'm a Disneyland girl! You will not score an awesome hotel deal for DLH, Paradise Pier, or Grand Californian the closer they get to dates. They don't seem to care if rooms are left unsold, maybe so people don't play chicken with the rates and the value stays inflated.
As PP noted your best bet is to book right away when a deal comes out. I've noticed that rates can change quickly because many times I've found a great rate (like maybe there is a better level room at almost the same price as standard) but I took a minute to double check rates on Orbitz/Expedia, then when I rechecked the rate or changed the date and changed the date back to the great rate date, that better price is gone. Maybe they have just a few rooms with better deals, then it reverts to whatever the special rate is. Who knows.
I think a good rate for DLH would be anything around $350 for standard.
You could book a room off site now, and call Disneyland reservations starting at one week before your trip to see if they have a rate available that is reasonable to you. You have to cancel Disneyland hotels 5 days before your trip so one week out you may have some luck as people cancel their reservations. That still gives you time to cancel off-site reservation, most of those will be 48 hour cancellation.
ETA book now, and if you do see a better rate later, cancel and rebook. I have gotten them to adjust my reservation once, but I don't believe that is the usual policy, so cancel and rebook works best.