We're a family of 5 and we fly SWA almost exclusively. I never bother with EBCI except when we're coming back from a cruise because I won't be able to check in 24 hours before. This past summer was the first time that all 5 of us couldn't find a seat together. Even then we were able to sit 3 and 2. If you're worried about it, purchase EBCI and go straight to the back of the plane when boarding. I know people say to wait to buy air, but a lot of that depends on the route and time of year. There have been times where fares dropped a little as I got closer to the trip. Most times though I've watched fares go up.