Question about 737-900

I am looking at the data, and why would someone pay more for the 900 version? Same capacity as the 800 with less range. What am I missing?

You have missed the real-world price. An 800 simply costs more than a 900. If you look at the fuel flow, see which aircraft has a lower fuel flow. A lower fuel flow decreases fuel cost, leaving more room for profit.

In real-life, the 900 (non-ER) is certified to the same max seating capacity as the 800 due to the number of exit doors. But it trades range for more capacity (floor space and cargo room). The 900ER has more exit doors, so the certified passenger capacity is higher.

In AE there is no reason to buy the 900 (non-ER) over the 800 because you can't put more seats in than the 800.

Would it be possible for the -900 to have a limit on seats fitted (somehow something to do with the range bit?) to 189, but have it able to carry 189 with decent legroom?

Would it be possible for the -900 to have a limit on seats fitted (somehow something to do with the range bit?) to 189, but have it able to carry 189 with decent legroom?

Not until we have cabin space / floor area data for aircraft. Right now we're just basing the numbers on max certified seating capacity.