There's a few things.
First, it is so important that your daughter identify and express her will. She clearly has one, which is great. The pitfalls of going from childhood to adulthood often involve losing your will and your trust in it. That she knows what she wants is a wonderful indication of good parenting on your part!
Second, your daughter, as a human being with feelings and a will, will express displeasure or pleasure with things, like she probably does with food. You know that a MacBook Air costs a lot more than food--she might be much less aware of this.
Third, it sounds like her concerns are valid. You didn't say she expressed any displeasure with her current computer and she has learned to use it in a certain way. She might not be like people here on Macrumors who decide to upgrade often.
Fourth, you say as a result of this you will be spending more time with your son, and you may have been joking, which is fine, but it could be indicative of something. As adults we come to realize we cannot choose the way people express their love to us. My mother is not the maternal type, but she's very good at throwing parties. I accept that party throwing is her way of showing love. A child shouldn't have to realize this. You feel your daughter rejected you because of the way you uniquely attach value to a computer and or money spent. That may not be how she wants or expects love from you. It's possible it never crosses her mind.
Fifth, there are some people, like myself and my mother, who are not good at receiving gifts. From a young age I would watch my mother react to gifts in a way most people would consider unbecoming. If she received a sweater from my grandmother, she would say something like, "Oh, this would have been so nice for Susan instead, don't you think?"
I am the same way. For Christmas last year, my "big" present from my parents was a new pair of eyeglasses. I was disappointed because eyeglasses seem like something you should pick out yourself and I needed a new prescription so it seemed like a waste to get a new pair without the new prescription. After a few months though, I was quite glad with the practicality of the gift. I would not have gotten a new pair myself or gone for the new prescription, and I wear out my glasses fairly quickly, so it was nice just to have a functioning pair.
But now that in my family we know that my mom and I react poorly to presents, it's an accepted thing and no one gets upset by it. Christmas and birthdays are a very hard time for me with receiving gifts. It's partially that I get well intentioned gifts that fall short. At my last birthday my only wish was for a blood glucose meter because I was pre-diabetic at the time and my doctor wouldn't prescribe me the kit. So, my mom got me one of the $10 kits with rebate at the drugstore but it didn't even include any testing strips. It was a pretty disappointing gift because the strips cost a fortune, but there were other smaller gifts and breakfast in bed.
The point is that in my family, we expect holidays and birthdays to be emotionally traumatic times and I at least expect very, very little, and it is accepted if I react poorly. However, I usually come around, as I did in the case with the glasses.
Often long term relationships don't start idyllically, like my relationship with the glasses. I'm suspicious of the ones that do. Perhaps your daughter will grow into the MBA in a way she wouldn't have if she weren't able to be honest about how she felt about it when she first saw it.
There can be other more complex reasons for your daughter's reaction. There was a sudden change that was out of her control! Why was she receiving the gift? Does she associate receiving expensive gifts with bad times in her life when you have paid her for guilt you've had over something? There are many possibilities.
My main suggestion would be to see the beauty of your daughter's will. She has one--it's the gift of life. She wouldn't be who she is if she acted exactly the way you hoped or expected. I think that you were very well intentioned; however, I have seen in my own family experiences the dangers of having self appointed experts exerting their will over people, especially in my family females, who begin to feel their opinions don't matter in the face of experts on technology, etc. I think you need to allow for opinion diversity even if according to an objective benchmark in your mind that opinion seems worse, especially with children. It's very important children make choices about preferences. And sometimes when they make choices contrary to what we would do, where you even feel bad because you feel like it's a waste, you can see they value something more pure than we as adults do. She might have liked a lunchbox with a giraffe as much as the MacBook Air for all I know. Everyone in my family told my sister to wait and not get an iPhone. We told her a new model was coming out soon! We said this for months. Finally in May she bought a new iPhone--and a white one! I bit my tongue and told her I loved the white! The thing is that she is SO happy with it. It shouldn't have mattered to begin with that I thought she should wait or not. She didn't care about having the latest generation. She doesn't even have any applications on the iPhone and loves it! Should I berate her and tell her she's not allowed to be happy until she's getting the full value of the phone? It's my instinct, but it's a bad instinct.
So with your guidance, my suggestion would be to seek her input into what she wants, even when your gut tells you that you know better for her. Because in the end, even if you get what you think is best for her, she's the one who will find value in it. And even more importantly, she will value her own sense of her judgment depending on how you react to her.
I don't intend any of this as a criticism. You are father of the year for caring and just being there.
