] Of course, the mitigating factor in S&S is Col. Brandon's goodness, and Marianne is not literally being *forced* to marry him

No, not literally, and not even at *all* forced to marry him. In fact, Jane Austen specifically uses the word 'voluntarily'.

] Also, no matter how happy their marriage, if Marianne makes it past her child-bearing years, she can look forward to at least 20 years of widowhood with very little chance of a *third* attachment, just like her mother.

So, she should not marry a man she strongly esteems, who loves her and whom she grows to love just as much because 20 or 30 years down the road she might be widowed? Colonel Brandon is 37 when he marries. It's not unreasable to assume that he could live another 30 years or even more. Mortality rates at that time were skewed by infant mortality averaged in to the population. Someone who had made it to adulthood had a reasonable chance to living to a decent age--particularly a man who had been a soldier overseas for some years and come back still healthy from that.

] I would still ask some hard questions before I let my teenage daughter, or any young woman whose welfare I cared about, go out with an older man, especially one twice her age.

This is still looking at it from a 21st C. mentality, which is unfair since Jane Austen was writing for an audience who lived in her time and did not have a problem with this type of an age difference. Also, 19 year olds (Marianne's age when she marries, just like Elinor) in that time did marry and were actively looking for someone to marry, and so would have been considered much more mature than we would consider 19 year olds to be these days.

People did not 'go out' at that time. From Mrs. Dashwood's perspective, Colonel Brandon is a decent, kind, good-hearted man with an excellent income and a fine estate, who has been sincerely and deeply in love with her daughter for some time. That's all the criteria anyone needed to be good husband material in that time. When you add to the fact that Marianne feels strong esteem for him and that the two enjoy a lively friendship together, there is no reason they should not be together in that time and that place.

Colonel Brandon himself was a little concerned that he might be too old for Marianne. However, he made absolutely no advances towards her of any kind until she began to show him that she had regard for him too. By that time, he also had her mother's 100 percent support for the match and even her promise to do all she could to promote it. Although others realized he was in love with her, all his dealings with Marianne were respectful and out of kindness and concern for her welfare. Nothing wrong with that either.

]it's things like this that remind me why I'm grateful that I live in my time, not in JA's!