I have a few different lines of thought. The OP asked for opinions, so that's what I'll give... of course at the end of the day it's not my decision. With that said, my thoughts:
2 days to make the drive is pushing the limits of impossible; even assuming sleeping in shifts and both of you splitting up the driving. When I was 18, I once did Philly->Phoenix in 48 hours. At that age, I could get away without more than about 3 hours sleep the whole time (was probably stupid to push it that much, but I digress). You're looking at a distance even further. Any time you stop, even to grab drive through, fill up with gas, or use the bathroom, you're adding on to the times that are estimated by maps.
How does your husband feel about this? There is a good chance that for at least the first day after the multi-day drive, on each end, neither of you is going to be feeling too alive and perky. In my experience, the number of hours in the car over such a long haul is far worse than any jetlag effect over three time zones. Every family/relationship is different, and you know your husband best. I can say in my opinion though, that if a 3000 mile drive (in each direction) was thrown on me as a surprise, I'd be beyond livid.
Apart from the fear of flying, cost was also mentioned. I've offered similar comments about this on other threads from time to time, but to summarize briefly here: you may not be "saving" much my driving. Sure, if you calculate miles / miles-per-gallon * cost-per-gallon, it's almost always going to come out cheaper than the cost of flight tickets. But, if you instead consider the total costs of vehicle usage, you might think differently. A conservative cost estimate of even 30 cents a mile (AAA currently lists an average operating/ownership cost of 59 cents a mile for a sedan) would mean a 6,000 mile round trip costs about $1800. That's before you eat, or potentially stay at a hotel, or anything else along the way.
Now, with all I have said, a lot of it still comes down to if you're much of a "driving" family or not. If everyone in your family enjoys road trips, and you work in a more realistic time table for the trip, then it may still be a great idea to drive. I'm just offering some other points to think about.