Kitchen And Dining Area
Speaking of kitchens.... This is one of the most critical rooms in your house, planning-wise. Your Hunger Need is going to be one of the most time-consuming Needs to satisfy, so you want to ensure that you can do so efficiently and with a minimum of fuss!
When your Sim goes to prepare a meal, they'll grab the ingredients from the refrigerator, prepare the ingredients (you can use a Food Processor to reduce the time this takes), cook them on a stovetop or a range, then make some final prep on the food on a flat surfacetop before bringing the meal to the nearest chair and munching away. Thus, it's best to have all of these objects in a line in your kitchen, with enough space for your Sims to maneuver between the lineup of appliances and the seating arrangements. (Note that not all recipes use all of the appliances. Low-hassle recipes, such as Cereal, are quicker to make, but won't replenish your Hunger as much as something more elaborate. You may need to improve your Sim's Cooking skill in order to unlock recipes that can actually use all of the items in your kitchen. Note also that the quality of your countertops will increase the speed of food preparation and the quality of the food!)
The quality of your appliances does have an impact on the quality of your recipes. The main exception to this are the refrigerators. Since there are only two models available as of this writing, and both satisfy the same Hunger requirements, you shouldn't feel compelled to upgrade to the more expensive Ciao Time model before you can safely afford it. There's also only one kind of food processor, so there isn't much you can do in that arena.
Your stove can make a huge difference in the quality of your food, however, and there are a few choices here. If your Sims cook their meals with any regularity, you'll want to plunk down the dollars for an Elegant Chef Flamebay Gas Range as soon as you can feasibly afford it; it offers ten times the Hunger satisfaction of the cheapest model at just over twice the price, and will let any chefs in the household easily fill up their roommate's Hunger needs with a single gourmet meal. You can also choose to "cook" foods in a microwave or toaster oven, but these are very inefficient when you compare the results to the time it takes to use the appliances and eat the meals.
If you plan to throw parties or entertain often, you'll also want to have a coffee or espresso machine somewhere near the seating area. Coffee packs a bit less oomph than espresso does, but more servings can be made. Your guests can't use these machines on their own, so you'll need to choose the Serve option in order to make a separate portion for your guests.
Last, but not least, is the dishwasher. It's a good idea to spring for a dishwasher if you can afford one, as they're much more efficient timewise than manually washing dishes in a sink. The less expensive model, the Wishy-Washer, is noisy enough to wake up Sims sleeping nearby, and also has a higher chance to leak than the Whisp-Aire. Either model will fit into a countertop, thus letting you place a small appliance, such as your food processor, atop it.
If you have room left over after all of this, it's always worth your while to ensure that there are two or three flat surfaces near your stove and seating area. These will let you make multiple trays of food or coffee for parties, without having to worry about cluttering up your dining room table.
When your Sim has prepared a meal, he or she will head for the nearest chair/table combo to sit down and eat. Although it may appeal to your sense of aesthetics to have a separate dining room that's separated from the kitchen area, in practical terms this isn't a good idea, as it will increase the amount of time it takes to eat a meal, which is already time-consuming enough. Instead, try to get your dining room table as close to the stove or countertop where meals are served as possible, but leave enough room for guests to maneuver. Having two spaces between the countertop and the first row of chairs at the table is a good rule of thumb, although you can drop down to one space if necessary. (If the chairs are flush up against the countertop, then the row of appliances will be useless.)
Since it takes so long for your Sims to eat, you'll want to ensure that you're fulfilling their Comfort Need as they do so. To do so, buy the most expensive chairs you can afford, checking to ensure that they have a decent Comfort replenishment score. Chairs are very expensive for items with such little functionality, though, so you may not be able to go all-out in this area. If you can only afford one or two nice dining room chairs, place them on the side of the table closest to the food preparation area, and place any cheaper chairs on the far side; this will ensure that your Sims use the nice chairs during their everyday lives, while you'll still have plenty of seating for guests.
So far as the table itself goes, you can afford to go cheap here; the table doesn't provide any Comfort at all. The more expensive tables will give you some Environment, but even the cheapest table will be able to seat plenty of guests. The most efficient seating arrangement is usually a 2x2 table with eight chairs around it; Sims will share a corner of the table with another Sim, so this should be suitable for all but the most raucous of parties.