For domestic and Club Europe, front row (and can be several rows): Gold and above
Front block after that, can be 4 - 10 rows quite easily: Silver and above plus some corporate customers
Behind that: selectable if on flexible tickets (etc).

EuroTraveller: All seats are available for selection, however potentially chargeable if HBO or non status or inflexible tickets. There is a block of rows reserved for the moving curtain, so that Club Europe can be expanded without disrupting everyone. No one can sit there until about T-72 hours

At T-72 everyone can select any free seat in their cabin, but non status and HBO potentially need to pay, domestic and ET.