I'd recommend the Altis.

The newer 1ZR-FE engine is actually economical and isn't prone to the sludge issues you fear with the 9th gen (ZZ engine). I can only speak from experience with its bigger brother, the 3ZR-FE, which hasn't had any oil-related issues even though I only change oil every 10,000 KM.

The 1.6 Altis is also known to be fuel-efficient, despite its rather old 4-speed slushbox. It's about as good as other automatic subcompacts (~9 km/L in regular city traffic) but has more low-end torque so it putters about without any hesitation. It's also very stable on the highway, and the comfortable ride means long drives won't be as stressful as in other cars.

The shortcomings of the Altis (less-than-stellar space, feather-light steering, uninspiring handling) don't seem to be of primary concern for you or your wife so I really think it fits your needs pretty well. Whether you get the 1.6 G or the more loaded 1.6 V, the pricing seems reasonable given the features of the car.