Now that almost everything is internet-connected, serious consideration needs to be given to how to make them play well with your house -- it's no longer enough to place a wi-fi base station and connect everything to it. One user streaming a HD movie will saturate the network and will ruin performance for the rest of the users.
If you have a newer house with Structured Wiring (CAT 5 or better cable placed from each room to a central closet), you're in great shape! All you have to do is complete the wiring and this will only cost you a few hundred dollars in parts.
But, if you have an older house, the answer is much more complicated. You're going to have to consider several different solutions and you'll probably need to use all of them to get the best performance.
Wired Ethernet Network
Even though an older house isn't prewired for internet, a good start is to wire as much as the house as you can. In a single story house, or any house where you have access to a room's walls through the attic or basement, this is the best way to ensure a reliable, fast connection. There are plenty of sites that give the gory details on how to fish the wires. The only tips I have are to try the MagnePull wire fishing system -- I found it works better than fishing tape. Also, run more cable than you need -- it's just as easy to run three cables as two and it will save you lots of time if you ever decide you need another connection.
Expect fishing and wiring to take an hour or two for each outlet. Yes, this is time consuming, but each device you can get onto ethernet leaves bandwidth for the other alternatives, which are slower.
Something else you might try, but it is a long shot, is reusing your existing telephone wire. Older houses usually have telephone wire strung as a daisy chain, which means the cable runs directly from outlet to outlet and isn't in a home run. If the wiring is CAT3, it has eight conductors, like CAT5 and can be reused for ethernet, at the possible expense of speed. To reuse the wire, disconnect the wire coming from the target outlet from the other outlets and splice it to CAT5 or better cable in a convenient location (probably in the attic above the room).
It might go without saying, but make sure that your switch supports Gigabit Ethernet. This is the benchmark for wired networking speed.
For those rooms that you can't get to, you're going to have to consider one of the other networks.
Wired Network Over Powerline
Next up is Ethernet over Powerline (HomePlug AV), a network that runs over your household's electrical wiring. This setup uses two devices that plug into your electrical outlets -- one near your ethernet router and one in the room without access. The system works okay. In my experience, you can expect 20-30% of ethernet speed. Because of split-phase wiring, it's very particular about where the two devices are placed and this network's speed will depend on good proximity.
Probably the best part is that installation is dead simple. Plug the devices in and a few seconds later, they're connected. I'd use this network for desktop computers and other devices that aren't mobile.
Wired MoCA (Coaxial Cable) Network
One set of structured wiring that your house probably has is coaxial cable for television. This wiring has its own network called MoCA (Multimedia over Cable Alliance). It's pretty fast and the speeds are reliable, but the problem is that there's aren't many hardware choices. But if you have Verizon FiOS, good news! FiOS routers and DVRs have MoCA built in. Also, if you have TiVo, the newest TiVo Premiere Elite also has MoCA built-in. This is a big benefit, because it take high-traffic multimedia content and puts it onto its own network. In fact, because of the poor hardware choices, I have chosen to only use MoCA to network my DVRs.
And this leaves us with wireless networks. You almost certainly have a wi-fi router already, but you're probably due for an upgrade. If you live in an urban or suburban area, you're probably surrounded by other networks and you're likely sharing bandwidth with your neighbors. The best thing you can do is make sure that your router is one of the latest generation devices that supports 802.11n on the 5Ghz band.
If you have one of these routers, I would make the 5Ghz band (n) only and I would point as many devices as possible at this network -- this will probably be your laptops and this will ensure that they get the best possible throughput without interference from your neighbor's networks and with the advantage of having as much of the other traffic shed onto the wired networks.
Point all other wireless devices at your 2.4Ghz network that supports b/g/n protocols. I wouldn't expect the throughput to be great, but it will be way superior to having everything on the same wireless network.