A couple of things come to mind...most of the time it's women who call to make the reservations. For women, a vacation has meaning beyond being away from home or work. Sometimes it seems everything we do is fraught with subtext. Look at the holidays...how many guys stress over whether or not the tree looks as good as the one last year at someone else's house? How many husbands would open the door and let in all the holiday guests while 3 little kids are running around in their undies? The same number of guys who didn't notice the kids were in their undies so did not try to get them dressed and the same number of husbands who are wondering what they did wrong when a shoe comes flying down the hallway at them. The woman in this scenario wanted everyone perfect before the door was opened. The guy just said to himself, 'Doorbell's ringing, open door.'
More guys 'go with the flow' and take things as they come than women. More women worry whether or not everyone on vacation is having a good time. In my brief experience here and with all the men I've grown up with, guys don't care so they don't stress so they don't 'pitch a fit' when something isn't perfect. However, I've noticed more older women saying 'to hell with it' and not caring if her husband is enjoying his vacation, she's enjoying hers. Someone else is cooking, someone else is cleaning, someone else is picking up after her and her husband.
I've been glad many, many times knowing I do not have to drive 6 hours in the car with a couple who have just gone thru vacation meltdown when the guy says, 'Hey, c'mon let's go, we'll get home just in time for me to go over to Bob's house for the game,' while the wife is looking at a week's worth of dirty laundry and realizing, once again, tag, she's it for the garbage detail and he's fat, dumb and happy and off to the game with his friends.
So, how to offer that woman the vacation she wants and needs? If they've never been here before (so have no idea what all there is to do) I try to provide them with options for things to do. When they try to clean their table at breakfast I say, 'Relax, that's my job, you're on vacation.' When they are on the phone, I try to understand that planning someone else's fun is not fun. And also realize that SHE may have been ready 2 months ago to make these reservations and HE just got around to saying ok, so now she has fewer options and she's really mad at him, but I'm going to get the brunt of it.
BTW, here it's always been the guys who have yelled on the phone and called me names. You may get more cranky women because of the spa side of your biz.
I think your offering her the option to go elsewhere for a better experience (because it was too short notice for you to do everything she wanted) was the best you could have done in that situation. I try to commiserate when I can't help someone. 'Oh, I know, it IS so hard to make reservations around everyone's schedule. Here, let me give you the number of a place that I see has 4 rooms open tonight.'.