The SpectersOnly two Sims dwell in this household: Olive, with the Knowledge Aspiration, and Ophelia, who's oriented towards Family goals. There's not a lot of love in this house; Olive leans heavily towards the Grumpy side of the equation and will take a lot of delight in aggravating any visitors that come along. Ophelia is a bit more kind-hearted, so you should focus your socializing efforts on her, while trying to minimize the damage that Olive can do.
So far as the house goes, this, like the Grunt household, has a doorway that's set well away from the front of the lot. If you can afford to do so, you may wish to shift the gate over to the left a bit and build another entrance to the house that's closer to the sidewalk.
The first thing you'll want to do for this house in order to make it livable is to get it some items that build up Fun--it's incredibly low on them in its default state.
The SmithsAh, the gloriously average Smith family. Your normal, happy clan: mom and pop still in love with each other after all these years, son Johnny on the cusp of adulthood, little Jill wanting nothing more than to be like her big brother. Oh, and the dad and son are aliens. Yeah, there's that.
Luckily, upon first entering the household, you should be able to get a few Wants completed for just about everyone. Pollinator Tech and Jenny are both Family-oriented Sims, which is a wondrous congruence in this game, as many of their normal romantic interactions will give them Aspiration points. If you want to, you can throw a party for Johnny and have him invite his friends over; it won't be too hard to have a good party as soon as you enter the house. If you just want to send him packing, though, you can just tell him to blow out the candles on the cake (it's near the door leading to the deck), and he'll grow up instantaneously. If you wish to keep him in the household, feel free, but you might benefit from having him move out, if possible.
One of the things that you can get rid of if you wish to have a bit more money is the pool. Pools are unnecessary for most homes; they're nice enough, but they can distract guests and fragment your parties. If you want to sell the pool, though, you'll gain an easy 4,000 Simoleans or so.
You may want to shuffle the layout of the first floor around a bit so that the kitchen and master bedroom switch locations. It's always worthwhile to have your kitchen near the main entrance to your house.
The CuriousesThe Brothers Curious, Pascal, Laslo, and Vidcurd, are all oriented towards the Knowledge Aspiration, making this a rather studious household, albeit one without many friends. One of the main problems with the Curiouses, in fact, is that there are only about three friends between the brothers when you first start out. You'll therefore need to take advantage of every opportunity for social bonding that arises in the course of the Curious's days; eventually you may want to bite the bullet and start a party. There's a large outdoor area that is easily gussied-up for a large gathering, if you're willing to manually move some of your Hunger and Fun items out-of-doors, along with enough seating for everyone.
The huge set of walkways leading up to the telescope atop the house looks interesting, but it's actually quite pointless, and in fact causes your Sims to sometimes walk well out of their way to get to that sole item. Move it down to the ground near one of the doors, or near where the carpool arrives, and sell off as much of the staircase as you can. If you want to keep it for the cool factor, you can at least sell the pillars, which are worth quite a bit of money.
Note that there are two expensive televisions right on top of each other; this obviously isn't a very efficient use of space. Since you'll be rather strapped for cash upon first entering this scenario, you should sell the cheaper one; if you want to keep it, you should move it to another "fun" area, perhaps near the seats and grill outside.
One thing that the house is lacking are Environmental items; everything included is intended to be functional. Thus, a large portion of your early paychecks should go towards paintings, decorations, flowers, and the like, so that your visitors aren't consistently moping about in a sterile techno wonderland.