Where to Stay en-route LA-San Diego-Las Vegas-Orlando-Washington DC-New York

We are a family of 2 adults and 4 children (ages: 3, 5, 8, 9) and would love to do a roadtrip in the USA in a RV.
Our dream roadtrip would be to fly into LA (from Australia) and spend a few days exploring the sights, drive down to San Diego so my son can fulfill his life long dream of going to heaven....I mean Legoland. Perhaps check out the Zoo too whilst we are there. Then we thought of driving to Las Vegas and Grand Canyon area.
Whilst we are in the USA we would love to visit Walt Disney World in Florida for 6 days (and perhaps do the resort thing for some R&R) and wondered if it is too far to travel in a RV?
We would also like to revisit Washington DC and New York and wondered if it is worth driving from Orlando?
Is it against the law or too unsafe to pull up roadside on long trips and camp for the night in the RV? Do you have to stay in campsites?
Obviously having never done this sort of trip before we have a lot to learn so all help would be great. How long should we allow to do this sort of trip?
We were thinking of going around November time.
Thanks

Welcome to the RTA Forum!

As far as a timeline goes, you'll need a week just to drive fairly quickly across country. Throw in all the things you've listed that you want to do, including spending a week at Disneyworld in Florida, and I think you'd need a full month for the trip.

You can't just pull off to the side of the road to "camp" in an RV, but there are some free places you can park, like truck stops and some store parking lots - like Walmart. However, when you are using these free options, it means you won't have things like water and power, and pushing out the slide-outs of an RV is frowned upon, so you could end up being pretty cramped with all the people you are talking about.

It is neither safe nor permissable to pull up along the side of the road, and in some States not even in wayside rest areas. As already mentioned, even at truck stops and such you would be very cramped.

But I am wondering why you would want such a large RV, as you would need for your family. It will cost quite a bit more than hiring a vehicle and using hotels / motels. Remember a large RV will also give you parking problems when you pass through and stop in urban areas.

Have you thought about hiring something like a Suburban, a very spacious people carrier, with tons of room for luggage to boot! Can't really compare it to anything at home... don't think we have anything as large as that.

Have you thought of flying from the west coast to the east coast and renting at either end. It is a long trek cross country... think Broken Hill -> Perth. Unless there are particular places you wish to visit along the route, I would re-think.

Lifey who has driven solo from coast to coast several times