I'm a huge wagon fan and have researched this extensively with similar criteria to the above. I even created a spreadsheet comparing the various lightly used wagons on the market (Allroad, A4 Avant, V60, BMW E91, TSX, etc....). This was all to decide on a replacement for my VW diesel Sportwagen which is being bought back. A couple of interesting things arose:
1. The only Wagon (excluding the Outback) that has as much space as the VW Jetta Sport Wagen was the Acura TSX. It has a relatively large cargo area and back seat. The E91 BMW and Audi A4/Allroad have slightly less cargo with back seats down, slightly less back seat space, and far less cargo with seats up. The TSX is wonderfully reliable and well made. Only downside is that it is FWD only and the power is adequate, but not great. Engine should run forever though.
2. The Volvo V60, while great looking, is practically a hatchback as far as function goes. It has similar cargo space to a VW Golf/GTI and less back seat space. Partially due to the sweeping shape of the back window. Great looking car though.
3. The E91 BMW wagon is actually a very reliable car and shouldn't be bad to maintain if you have a good independant shop. This is the last of the great straight 6 naturally aspirated BMW's. As I recall the 2009-2012 versions have less problems than the pre 2009 versions. The engine in these has evolved slowly over decades and is pretty bulletproof now. I was leaning in this direction until......
4. I realized that the current generation VW GTI was quicker and more fun than all of the above options, while getting superior gas mileage. It also has a larger back seat than all of the above wagons which is important for my pre-teen kids. The cargo area almost matches the Volvo and E91 BMW with seats up and I have a Yakima Skybox that I can use when I need more space. Also, my wife has an Odyssey. :)
Be careful pushing the wife in a direction she doesn't 100% want to go. I've made that mistake. As much as I hate crossovers, she may strongly prefer one. The E83 BMW X3 is built on the E91 chassis and is basically a lifted wagon. Food for thought. You might also consider something new like the VW Alltrack.