If you could get me the exact date(s) of travel that would be best, but I've just taken a look at the seatmap for a random day in March (in this case, 3/21) and it looks like NH7&8 are operated by a four-class 773ER aircraft.
Looks like the regular ANA Business cabin (
https://www.ana.co.jp/int/svc/w_en/c/seat/777_300er_01/) with 2-3-2 seating.
Straight off the bat you'll want to choose the center seats (D/F/G) if you want to sit together (as a family I assume you do).
There are three business cabins- the first mini cabin of two rows, the main business cabin of 8 rows and the last mini cabin of 2 rows.
The first 2-row mini cabin (rows 3 & 5) is directly behind the First Class cabin. You might like the mini cabin as it tends to be quieter and feels more private. There are three lavatories and the galley behind this cabin. No windows for row 5 (5A & 5K).
The main cabin (rows 6 ~ 14) is behind the lavatories and galley mentioned above. Avoid the first row of this cabin (row 6) as it might be a bit noisy due to proximity to the lavatory and galley. Other than that, all the seats are pretty much the same. Right behind this cabin is another lavatory and the self serve bar. There is a selection of packaged snacks and packaged (non chilled) drinks placed here- nothing special, you'll probably want to order the a la carte hot food instead
The last mini cabin (rows 15 & 16) is right behind above-mentioned bar and lavatory. Like the first mini cabin, it is likely to be quieter and will feel more private. Right behind this cabin is the Premium Economy cabin.
You'll need to give me the date of travel before I can tell you which seats I'd personally choose though
