I've never stayed offsite, so this is first time driving. So...do you pay the one fee for the day and can drive to all the parks? They don't charge you again for changing parks do they? Also, there is a courtesy shuttle at the place we are staying but it leaves at weird times, never before 10:30 a.m. and you have to coordinate where you are and where you have to be to get back, it doesn't go to every park. I'm thinking it may be really challenging to figure it all out and not compromise your day. So, if we have to drive, what should our strategy be?
We always stay off property - we can get a week in a condo for free from my father-in-law or for a very low price through my company. We've never had a problem getting to the parks from offsite since the road signs are so good - you don't need a GPS. It does get a little tricky where they are doing road construction at Epcot Center Drive and Buena Vista Drive and trying to go to DHS, but that's only temporary. IMHO, driving to the parks while on Disney property is a lot easier than driving in Orlando outside of Disney property!
As other's have said, you pay $20 a day to park and its good for all parks if you hop or want to go back to your room and take a break. And Disney parking is the best. I wish all other events had parking lots as good as Disney's. Simple to get in, simple to get out.
Driving gives you way more flexibility in what you want to do when. If you want for a shuttle, you are waiting for them and having to base your arrival and departure on someone else's time. We drive because we want to maximize our time each day in the parks, so we get there before RD. And, if you want to go back to your room to rest mid day, you get in your car and go without waiting on a shuttle.
Give driving a try. You'll find out that its easy and you don't have anything to worry about.