If you haven't read Alicia's last post about happy families at amusement parks, you might want to read it before you read this post. And then read the comments, particularly the one from Green Knight. In fact, let's just move that comment to the front page:
The happy family is an interesting problem. (As a reader, I'd hate a book with that theme, but that's another matter. But it offers interesting possibilities for setting up an undercurrent. The 'frantically happy' would not have occurred to me, but I would take it a step further and add an element of pressure. Both the theme park and the waterskiing will fit into that, and I'd sharpen that - a family trying to fit as much happyness into a short vacation as they can. Getting up at the crack of dawn, rushing the kids into the car (with laughter and jokes, but still pressure), a drive through rush-hour traffic, trying to get to all the rides (rather than enjoying the ones you love over and over again, no you have to pack all the experiences into it. Fast food, because there is no time to stop - they still haven't done all the rides, the kids chivvying each other along, leaving at the last minute, everyone on a high.
I like the idea of showing them happy - *but* they're working hard at it and nobody could keep that up for long.
And I'd go for background details that play with that picture -one of the kids gets a toy catapult, but the elastic snaps. Daddy fixes it, but still. The high speed train that could be seen from the road, sleek and powerful - but they come to the train crossing and have to wait for it.
Green Knight, I like the way you think. Adding pressure adds tension. This shows how tension is different from conflict, actually. A marvelous day, memories in the making, can still have tension. The people are getting along and enjoying themselves. How boring! A dash of tension is just what the reader wants to keep turning the pages. Alicia describes one very subtle way to add tension, that is, by ramping up the joy until it appears fragile and unreal. The reader absorbs all these cues and learns not to trust the bare facts. This creates tension because on the one hand, the reader is absorbing all this surface happiness, and on the other, they know it's false.
So I'd either ramp up the sense of impermanence and frailty in the happy day (show the ice cream melting, show the flowers wilting), or I'd cut the opening in the theme park and just show the family trudging through the parking lot, exhausted and blissed out. Show the effects of the perfect day without making us read the blow-by-blow. Your novel isn't a travel piece or a sales brochure. It's a novel, and the engine that drives a novel is tension. If you can't load enough tension into the happy day to make it interesting, then cut it.
Alicia and I debate this point pretty regularly -- and, as with most of our debates, the point will never be resolved because the real answers are case-specific. Theme is important. Theme needs to be set up early. Is setting up theme, by itself, enough to carry a scene, or any part of a scene?
I lean toward wanting more than just set-up. This is true regardless of what you're setting up, be it theme or setting or character. I don't prefer a slow buildup to the initiation of the conflict. Some set-up is required, of course, but the sooner the conflict is initiated, the sooner the reader becomes engaged.
Conflict is tension on steroids. You might not initiate the conflict until page ten, but pages one through nine will still need tension. Start with the happy family having the perfect day, if you like, if you think this is an effective way to lay the foundation for what follows. Just don't bore me while you're doing it.