I'd wait until the 50k bonus mile offers come back around again (or make sure you apply through the right link), because then you only need to come up with 10k in spend to get the CP. If you apply for and get approved for both the premier and plus cards (I think) you can get 50k each towards the 110k required for the CP.

I'm not a big Southwest fan/flyer, so look around Flyertalk and there are also about a million blogger posts out there about the companion pass. I travel alone 90% of the time so the CP has never been on my list of achievements... #foreveralone