Yep, credit cards are the best way to get companion passes.
Option 1: annual pass
- Delta (DL) Platinum AMEX, Alaska Airline (AS) Bank of America, and the US Airways (US) Barclays co-branded cards offer companion passes.
- DL has a one year lag with no waiver of the annual fee, thus you won't get the companion certificate until you renew the card. However, this card provides the most benefits with a free bag per person (up to 9 including card holder), priority boarding, and a few others.
Finally, you could get a signup bonus of 25,000 slymiles after certain spend in three months. Delta award tickets are a bit tricky to find at low levels, but the card also offers the option to use the miles at $.01 a piece to offset the price of a regular ticket.
- AS provides the companion certificate right away with no waiver of the annual fee ($75) that costs $99+taxes/fees for the companion. Plus they have a signup bonus of 25,000 miles which is good for a round trip ticket. The card lacks in other amenities (like DL) and AS' network outside the West coast.
- US has a certificate that allows two people to fly with the cardholder for $99+tax/fees each and the annual fee ($89) is waived for the first year. However, US has some blackout dates, so you'll need to look into those. The card does offer 30,000 bonus miles, which can also be used on any Star Alliance partner (United, Air Canada). It offers priority boarding and check-in, too.
Option 2: Miles
If you have good credit and are responsible with money, you could play the credit card miles game. Many credit card firms (Chase, AMEX, Citi, Barclays, Capital One) offer their own and co-branded cards that come with bonus miles upon signup and after a certain spend (usually $500-$3,000 in three months). The Southwest Airlines card from Chase that was mentioned is one such card. These miles/points can then be used to purchase free tickets (+taxes/fees) to MCO.
I started last year and have all the above mention companion cards. While we have yet to use one (soon), DW and DD traveled to
Disneyland for free in May (DL Skymiles flying on AS). Plus, we have over 50k Ultimate Rewards points from Chase that can be transferred to Southwest or United for travel (or British Airways for travel on American Airline (AA) or Amtrak). I am sitting on the 40k US miles, since they will soon merge with AA and will convert into those miles, which then can be used on AS

). Lots of free flight options.
If you are curious, google the points guy and boardingarea for their sites. Boarding Area.com is a series of great airline and hotel blogs in general.
I started researching for a low cost/free option for our annual pilgrimage to the Mouse, especially since we try to hit both parks in a year. The annual fee is worth it in comparison to the companion ticket benefit, and the additional signup miles provide one additional ticket on a trip.
In addition to airlines, I also got the Hyatt card from Chase, since it has an annual free night at a category 4 or lower hotel (i.e. Hyatt MCO) for the $75 annual fee. basically a night at the Hyatt MCO for $75 (or another Hyatt).
Good luck and happy research!