I'm probably going to get flamed here, but I'm going to stick my two cents in as well. I'm a SW flight attendant. I have been flying for SW for 14 years now.
My first suggestion is that everyone go online and get your boarding passes early. For those of you that have not flown us in a while we board by letters A,B,C now not numbers. Groups A and B each hold 45 people and C the rest. Our flights in and out of Orlando are not only full but full of families. I am based in Dallas so I cannot speak for Orlando, but have not heard that we don't use pre-boarding. You can pre-board if you have children under 5 and I encourage it because it gives you a few extra minutes to get settled and get out of the aisle so we can board everyone else and get in the air. Keep in mind the FAA requires that car seats go next to the window. This is a safety issue, if the car seat sticks out over the seat and is put in the middle seat, the person next to the window is blocked in in case of an emergency.
My second suggestion; for the families that are not able to board in A or B, I cannot speak for the other 7,000 + flight attendants but I personally do everything I can to get families together. Nothing works better than offering free drinks to the people that move. Also, asking a business person if they wouldn't mind baby sitting this little one for the next few hours usually gets people to move as well. Many of our passengers are parents and understand and usually don't mind moving. I hope that every flight attendant you encounter is helpful and friendly and if they are not do not hesitate to write a letter to SW (just don't tell them I told you to

). We pride ourselves on customer service and you never know maybe they just need one more letter on this person to take some action.
About the assigned seats, I hate to tell you that our CEO, Gary Kelly, has announced that we will not be doing this. We are however going to discountinue service to Houston's George Bush Intercontinental Airport. Which is a bit sad because this was one of our original cities way back when.
If you haven't flown us in a while, give us try. You may just be pleasantly surprised with the changes you'll see.
Staylor