With the DVC membership, we get a $100 discount on the annual pass or a $125 discount on the premium annual pass. Those usually work out to be the best deals for us, so we tend to use annual passes instead of other ticket options.
We also only go once a year, but we plan our vacations so we can get two trips out of each pass. I travel with a school teacher, so our only option is to go on his breaks -- which means we go between June-August each year.
On the year we buy the pass, we'll go in August. The following year, we'll go in July, which allows us to use the same pass.
The TIW card is available to Florida residents and annual passholders. The cost of the card is $75 for one year. (You only need one per group.) With the card, you get 20% off your entire bill (drinks included) at most WDW restaurants. Whether the TIW card is right for you is something you'll need to do some math on. Some people prefer the Disney Dining Plans, others find that the TIW card is the better deal. If you don't spend much at Disney restaurants, you may find that you're better off without either. (You may have heard of the Disney Dining Experience, which is what the Tables in Wonderland program was called prior to a few months ago.)