Not quite 20 hours, but we drive from the Chicago area for each trip. It's ~18 hours, but traffic/weather can quickly change that estimate.
to WDW
We drive without any stops on the way down to WDW. I have worked third-shift hours before, so the lack of sleep really isn't an issue. Driving overnight minimizes the traffic, and it feels like we're not totally 'losing a day' by not flying. We'll check-in when we arrive and shower up. After a nap, we'll still salvage a couple hours of WDW-time before we go to bed fairly early.
to HOME
We've changed our strategy up lately. The drive home is more grueling because we're tired from the WDW excitement, sad we're leaving and we don't have an awesome vacation waiting for us on the other end of the drive. In the past we would check-out early in the AM and drive all day to get home. Now we linger, staying a half-day more. We'll go to MK and do a ride or two, but mostly just soak it all in one last time. We'll leave at lunch, with the goal of driving at least half-way home. We'll get a 1-night hotel in TN/KY to sleep a few hours, then wake up super early to get home. In the end we're paying a tiny bit more, but we're also getting a half-day more in the park than we'd usually do. And instead of getting home at midnight only to sleep in the entire next day. We'll get home at noon-ish and still have the rest of the day to relax.

Having a car is ideal for dining, especially if you're utilizing resort options. It can save time in many situations. It's also just nice to have when surprises come up or you want to go off-site easily. You can pack more if you want, because you're not limited to what the airlines set. You can bring your own supplies or you can drive 15 minutes to shop for them when you get in. Even if you only use it once or twice, it's great to have as an option at your disposal.