Is it worthwhile upgrading seats on Vietnam Airlines A350?

Flights & Airfares
1

We are flying VN 780 (a350) and VN138 (a321) From Melbourne to Ho Chi Minh, then Danang during the day.

Paid for economy class.
Qantas classic rewards were available but better value found with paying cash.
I’m slim 6"3 and prefer the comfort.

Vietnam airlines use OptionBox for various upgrades like lounges, seats, and having an empty seat next to you.

Strange that the Vietnam airlines website isn’t allowing me to select seats yet.

Upgrades available
Premium Economy $186 standby
Premium Economy confirmed $227 (still cheaper than using classic rewards option)

Business $869 standby
Business $1106 confirmed.

1 Empty Seat next to you $11
2 Empty Sears next to you $50

Any thoughts out there,
Considering it is a day flight, having extra seats either side for the price point is good value, but what stops another person moving.

Is the extra cost of premium seating worth it? Has anyone flown their service?

Thanks.

2

I think business is unnecessary because its a daytime flight but its deciding whether to pay a little for empty economy seats or more for premium economy. I personally think they have a really good business product and decent products on Premium and Economy. They are pretty standard fair but for a daytime, I would just pay a little to reserve extra seats.