On SWA I like to get group "B", as low a number as I can get. They board the families with little kids between groups "A" and "B". I want to know where the little kids (and very obese adults) are sitting when I choose my seat so I can stay as far away as possible. The worst flights that I have been on involved little kids, on one flight the attendant gave me free drinks because she felt sorry for me. On flights that are not full (VERY rare on SWA) my wife likes to pull the coughing trick to keep other passengers from sitting next to herAlways board in the "A" group. Southwest Airlines.
I stay away from American because of very unfriendly staff and flight attendants. Additionally, I hate DFW and avoid flights connecting through there.