Nintendo Wii Savy!

Get a balance board, too.
We use ours a lot and it is useful... per the exercises etc.

Start with choosing a couple of games. On the back of the package, it will show you symbols representing what you will need to play (ask someone at the store if you can't tell when you look, or if the games are secured so you can't flip it over to see the back).
Here's the rundown:
The "Wii-mote" is the main controller device that looks like a skinny rectangle, almost like a TV remote.
The "Nunchuk" is the little gearshift looking one that has a joystick on it. It is often used in conjunction WITH the Wii-mote (like skiing or MarioKart or Super Mario Galaxy2-- you hold one device in each hand and use both of them during play).
The remote plus is actually termed a "motion plus". It is a small little box thing that attaches to a standard Wii-mote. It's about the size of a 9V battery and clicks right into the end, inside the silicone sleeve. (I can't remember for sure if there is a different sleeve for the ones that have the motion plus attached, or not). It enhances the motion play... not sure exactly how it works, whether the bar picks up the sensor better, or it provides a 2nd stream of info out to the sensor bar, or what. But it makes the on-screen action respond more sensitively to the use of the Wii-mote. Some games really need this. Others, doesn't much matter (like Jeopardy! lol).
If you want to do any of the fitness stuff, you'll probably want to get a balance board. There is a lot of fun stuff you can play with that and the FitPlus game, or Sports Resort. It reads your core balance to help in moving the onscreen characters... like evading a snowball being thrown at you! Or hula-hooping. Lots of fun.

Most people say to get the chargers. We never did and it wasn't that big of an issue for us. You will easily be able to play all day long (that first couple of days even) on a set of batteries. Each Wii-mote takes 2 AA batteries, and the balance board takes 4, I think. I know the balance board came with a set of batteries in the box, not sure if the Wii-motes came with batteries or not. We have used some AA batteries in our house, but nothing obscene. You can certainly wait for a couple of weeks after Xmas to decide if you want to spring for chargers or not. Just buy one of those jumbo 24 packs of AA batteries to get started. They are on sale at Target right now. :)

As for all the "accessory packs" that are out there... tennis rackets, golf clubs, and the like... they aren't really necessary. I know some people actually prefer NOT to use them even when they do have them available. So def NOT a necessity. Again... you can always fork out for those later if you decide you want to add them.

hth

We have four controllers but only two nunchucks, you don't use them as much. The Wiimote plus helps stabilize the controller. I don't know if you played any games that require precision but it is next to impossible without the stabilizer.

I can't remember what they are called but they make charging docks. Either buy stock in a battery company or buy the charging docks!! Plus if you can train the buggers to put them back you won't lose the controllers.

My kids are playing the Xbox Kinect right now, those of some controllers I would like to lose. :p Loud!!

if you look on the back of the Wii games they will tell you whether you will need the nunchuck or not.

Every remote will also need a nunchuck. Some games don't need them, some do. It's for the movement in some games. You'll also need a charging station. We got ours for $16. You don't need the wii branded one. You can likely buy the wii remotes used at gamestop, but the demand this time of year is huge, so I'd start looking now.

Some games MUST have a nunchuck, some have it as an option.
I'd get the MotionPlus remotes for each player to start. You can always add the nunchucks later.