A tea factory tour takes forty minutes and they are broadly identical. Staying on an estate is a different proposition entirely.
Every hill-country itinerary includes a tea factory, and most of them are the same building with a different name over the door: a walk past the withering troughs, a cup at the end, a shop. It is not a bad hour. It is not a reason to come.
What a working estate gives you
A bungalow on a plantation that still picks is the version worth the night. You wake above the cloud line, the pluckers are in the field before you are up, and the cook has been feeding guests in that house for twenty years. The tea is incidental; the altitude, the silence and the food are the point.
How to tell them apart
Ask whether the estate still sends leaf to a factory, and whether the bungalow was built for the superintendent or for guests. A working estate answers both instantly. Anywhere that leads with its spa is selling a hotel with a view of tea, which is a fine thing to want and a different thing to book.
One night or two
Two. The first day goes on the drive up and the temperature change, and the estates are cold enough at night to be a genuine surprise. The second morning, when you know the paths and the kitchen knows you, is the one people describe afterwards.