A few ideas to fill and make the remaining empty seats out of sight. Not saying all of these idea are good, or workable, but here goes.
If and when the North stand is expanded, move the family stand to the front of the 3rd tier, along with with complementary tickets(EDS, staff, family, etc), who should be at the back of the 3rd tier.(empty seats out of sight)
Change the North Stand lower tier into a single standing end(safe standing?) for fans who want to stand and sing.(our end) This will make both the South and North stand lower tiers full constantly.
Next season. Those fans on the waiting list who miss out on a seat in the new South Stand 3rd tier should be offered similar priced season tickets in other parts of the stadium for one season, or for the duration of the North stand 3rd tier expansion. That way the additional seats along with the current(empty seats) have a chance of being filled on a regular basis next season.(extra matchday income, etc)
Make the 1st 5 rows(?) of seats along the bottom of the lower tiers cheaper, which may encourage better sales.
(I appreciate City have a sponsorship deal with Viagogo, but...) Get rid of viagagogo and do any spare matchday tickets sales(£5 admin charge?) in-house via the OS ticket page. It's obvious to the tie-up with Viagogo isn't working.(I appreciate I don't have access to ticket sales via Viagogo, etc) Yes, Viagogo works for the big games(Arsenal at home next), but for the small games there are 100's of tickets unsold, leaving empty seats scattered all over the stadium. City could easily and with little cost or disruption put a link on the OS ticket site for fans who have tickets to sell because they can't make the match, etc.
In general. Make match tickets easier to buy. I still think the OS ticket site could be improved to make buying tickets easier. Open all the seats on the seat planner, instead of individual blocks. On numerous occasions the ticket OS has stated the match is sold out, when it clearly sin't, with a link to viagogo for remaining tickets.(which don't sell) I'd like to see cinema type ticket machines outside the stadium, or in a building located next to the stadium, where fans can turn up and pick up their pre-booked tickets, or pick a seat/s via a touch screen and pay with a debit or credit card.
Allow any remaining unsold seats to go on general sales to non City fan card holders the day before the match, or on the day of the match, on a pick up basis at the ground only.
I appreciate City need to increase their matchday revenues as we are miles behind the likes of United, Chelsea, Arsenal, etc, but I hope when the stadium is expanded to 62,000 City will review matchday ticket prices as they are currently some of the most expensive in the PL, when they used to be some of the best value. ;-) (cheapest) Also. Most of our season tickets have gone up by almost 10% each season for the last 4/5 seasons.(I stand corrected on that) I think it's now getting to a point where a season ticket price freeze would be welcomed by the majority of season ticket holders, even if it was for only 1 or 2 seasons.
Fire away. :-)