Tim
To get back to your opening question, I think that Scotland makes much more sense than Bandon for a single 40-something avid golfer woman. As great as Bandon is, it is very much dominated by golfing parties full of beta-males, and to be honest there is no "there" there outside of golfing, eating and drinking. On the other hand, Scotland (and England and Ireland and Wales too) have history, culture, mystery and a sense of adventure as well as great (and greatly varied--Bandon is a much of a muchness--golf).
It's a no-brainer, IMO.
Rich
I am going to second this opinion. I just came back from Bandon; literally, I was there last week. I LOVE the place. However, I think I would choose Scotland/Ireland.
Most of my golfing life has been spent playing as a single, including a trip to Scotland many years ago, so I am very familiar with the situation. When you are at a place like Bandon, where there are typically groups of players, they stay with their group. I have found that people typically aren't as inclusive of others because they already have their group - their buddy or their wife. To be clear, I am usually the one telling the foursome, "let's meet at the 19th hole for a drink," so it is not like I am waiting for someone else to make the offer.
I am glad that Bill M. and Andy others have had enjoyable experiences at Bandon as a single (because that situation is not out of the question for me in the near future when my son goes off to college). However, given a choice, I think the chances of enjoying yourself, or the opportunity for an experience (like getting invited to the B&B proprietor's golf club; happened twice in Ireland) are greater overseas.
On the nights she doesn't want to be alone, tell her to cozy up to a bar in Scotland/Ireland, and you are guaranteed to have an enjoyable evening chatting up the locals. As friendly as everyone is at Bandon, it is different talking to a local in a pub than talking to the resort staff at the hotel bar.