veteran
I've been to the last 8 Festivals, and from what I've seen, a weekday visit would be best for a first-timer as far as checking out the booth offerings. However, there are a lot of 'special' events that are only offered on the weekends - some of which could be a good gift for your daughter.
For instance, on most Saturday nights during the Festival is the Party for the Senses, and it is fantastic. Cirque du Soleil performing in the venue - at least 20 fantastic chefs creating a signature dish, about 60 or more wines on offer - its a great party (but a bit expensive). Like many other special Festival events, it requires advance purchase - this year the special 'hard-ticket' events go on sale at 7:00 a.m. on August 16 - some sell out in a matter of minutes, so be ready if there's something you have your heart set on (the Party for the Senses does not typically sell out nearly that fast, and some times not at all).
The French Regional Lunches are excellent. There's a new lunch offered with the popular tequila tastings. There are many presentations, demonstrations, etc.. If you do a search, you should be able to find a guide listing all of the events (though I think one has yet to be released). If you have a developing foodie, you should look in to some of these offerings in addition to just wandering and trying the tasting portions. While that type of wandering and grazing can be fun, the best events (and the better food, by far) are the 'special' events.