A couple questions.
First---when you arrive in GCM, how far are you from your accommodation? And what is the check in time?
How far do you live from DFW airport?
I would stick with the non-stop. You are only 2 hours later and have the benefit of not worrying about any connection. You can get up and leave leisurely since you won't need to be at the airport until 11 AM.
Option of routing through MIA using 6 AM flight means you need to be at airport around 4-4:30 AM. Back up travel time and time to get family rounded up and out of the house and you are looking at probable misery. Additionally--your 1 hour connection in MIA is stress-inducing when traveling with kids. So you would arrive in GCM at 1 PM--but at what cost? A bunch of cranky tired travelers so you are truly losing that day. Risk of missed connection and increased risk of lost bags, god awful early departure with kids. Thumbs down for me on this option.
Option of overnight in CLT. Again---making it too complicated in my opinion. You land at 9 PM---so what time will you get bags, get to hotel and get kids settled? Maybe 11 PM? Then get everyone up in time to be at the airport at 7 AM. Way to much schlepping and transferring bags and kids. You get in at noon but when can you check in?
Seems like a lot of gyrations with the potential of missed connections and carting families around to save 2 hours. Especially at spring break when airports and flights are packed.
I would absolutely keep the direct flight and accept that 2 hours is not a big deal.