There are 5 of us. My DSs are currently just turned 7, 9 and 13. DH has a phobia about planes and refuses to fly unless absolutely positively necessary. We drive every where, all the time. Love it. It's an adventure. We schedule destination/sight seeing stops along the way on all our trips to break up the day (i.e., stopping at Ft Delaware or Statue of Liberty when we go to see my MIL).
Our longest road trip was from MA to CA and back. Or as I like to call it 28 states in 28 days our 7,000 mile odyssey. Loved it would do it again in an instant. Kids were 4, 6 and 10.
MIL lives in DE and since it takes longer to fly we drive there every year. 8 hour trip no problem. Leaving for DE in one month. Looking forward to it.
Drive every few years to IN to visit FIL and SIL. 19 hours there and back. No problems. Will do it again in a couple of years.
Drove to FL with DH and no kids in 93 no problems. Went to WDW, Key West. Took our time getting down there. No reservations so we just drove and had a blast.
Drove to FL in May - the three kids in tow - will NEVER do it again.
WHY?
1) We stayed in hotels each night, but the 13 hours on the road each day was just miserable. Too much time in the car. Even when we drove cross country we didn't spend this much time in the car (well, once, but that was because we misjudged how long it would take to drive across the rocky mtns - that was miserable too).
2) We had time constraints that made it imperative we stick to our driving schedule so we HAD to do the long drives - no time for a long break - we did stop at south of the border but really that's not a great place to stop anymore - avoid it.
3) It shortened the time we had available for WDW.
4) After adding up the meal/drinks costs, the hotel rooms, the tolls, the gas it cost almost as much money as taking flights. In fact with just one less person it would have cost the same

.
5) My friend decided to make an early visit - miserable - finding restrooms on that gotta stop NOW basis every hour was not fun. Having an overflow was even worse

requiring a change of clothes mid day.
That said, if you do decided to do it some things that we did to make the trip more bearable and less expensive:
1) Buy variety packs of individual serving size snacks ahead of time. That way you're not spending $10 each time you stop.
2) Buy drinks ahead of time and put them in a small cooler. Just like at WDW drinks at the rest areas are very expensive.
We only had a 10 days available to get to WDW and get back. If you have more time than that then I would say go for it.
ETA - please note that each time I had to stop for my friend my kids had to get out too. Which just made the stops exponentially longer. We can and will drive long distance again, possibly even to FL, just not to WDW where you have to stick to that schedule to keep those reservations or loose your deposit possibly your reservation.