The new Hyundai vehicles are all quite well built and have great warranty coverage. I'd add the 2010 Kia Sportage to my shopping list too, as it is about thre freshest SUV design out there. Neither the Santa Fe or Sportage is my 'cup of tea', but your wife is the one who will be the primary driver.
As for the 2.5L boxer head gasket issues- I spoke to a 20 year veteran Subaru tech at my dealer about the issue. He confirmed '98-03 HG's are a question of when they will fail not if. Said he's done a number of '04-05's but a lot of those had been driven REALLY hard and were all across the mileage range. The later years are 'one every now and then' but not much more often than Hyundai, Buick, Chevy and Honda which they also service. They service a few '09 Foresters that were sold to a medical supply delivery company and already have well over 100,000 hard miles on them and are reportedly holding up very well.
The biggest negative to the Subaru engine is the $$$ timing belt/tensioner/water pump replacement at 105,000, though to be fair-quite a number of timing chain equipped engines have tensioner and guide issues before that mileage.
You pay your money and take your choice.