In-Park lodging was something we always tried for in our pre-RV days, now we try for in-park camping

In July/August 13 I would like to take my 4 kids out west to tour some of our beautiful national parks. We have about 3 weeks, we are thinking of flying in and out of Vegas. So far we know NOTHING. rental cars in south new jersey Which parks? Which RV? Which gear? How much time to spend where? good planning tools? Any advice would be appreciated!
Vegas is fine as a launch point if you get good air fare when you want to go. I would do a loop from there and include Zion, Bryce, Capitol Reef, Arches, Canyonlands, Grand Canyon, rental cars in south new jersey and Hoover Dam for the basics and you could loop in either direction. Expect it to be hot in most of them in the summer, rental cars in south new jersey so give the kids a break with a stop at a motel with a pool every couple rental cars in south new jersey of days. Make reservations now.
Search here using the search box at the top of the page and put in the names of some of the places you want to visit. There are tons of trip reports that will give you information on possible alternatives. If you click on my name you can scroll down to a couple that I've done if you want a little rental cars in south new jersey basic information, but do look for some where folks have brought kids too.
You could fly into Denver and go to Rocky Mountain, Yellowstone and the Black Hills in 3 weeks. That would be cooler than the parks in the southwest near Vegas. It's probably more driving than visiting the parks that emalloy listed but very doable in 3 weeks. In the Black Hills you'd have Mt. Rushmore, Jewel Cave, Wind Cave and Custer State Park, and Badlands National Park is not too far east of there.
I think your first step is to figure out where you want to visit in general terms (Southwest, mountains or somewhere else) and then you can work on the specific itinerary, RV or not, etc. So ask yourself what type of climate and scenery you would prefer and weigh those options before getting real specific about gear and itinerary.
Day 1-3 from the airport drive to Estes Park and overnight at any of the hotels you like there. The drive is a bit longer, but we always stop at Whole Foods in Boulder and get picnic rental cars in south new jersey supplies for our first day in Rocky Mountain National Park. It is one of the bigger WF that I have been in and its right on the highway. I would have a meal in The Stanley Hotel-even if it is just breakfast(you could stay there). I really like the hike to Sky Pond-it passes a couple of really good waterfalls and includes The Loch area of the park. Of Course, drive Trail Ridge Road and Old Fall River Road
I hate to tell you this-- but Yellowstone, Tetons, and Custer may all be full already. You really need to get those reservations 12 months in advance(the day they become available-12 months is the norm).
For a different perspective, we had a small motor home when the kids were pre-teen and teen agers . . they are now in the 40's and still talk about how much fun our trips to the different National Parks were.
There is just nothing like wakeing up and cooking breakfast outside in the middle of one of the parks . . One of our most vivid memories is breakfast at a turnout next to the Black Fork of the Gunnison River just outside Yellowstone! !
As far as the RV goes, a great deal depends on the ages of your 4 kids. The older they are, the more room you'll need, which means a bigger RV. The bigger the RV, the harder/less convenient it is to make the trip without a towed vehicle to get around the Parks with. Finding a place to park can be a challenge in some of the Parks, especially rental cars in south new jersey in July/August. We have a 31 footer and there are only a few of the Parks we've been to that I'd attempt without our Jeep tagging along behind us.
In-Park lodging was something we always tried for in our pre-RV days, now we try for in-park camping. That's more important in some Parks than others, IMHO. Yellowstone in particular is best visited from in-Park lodging because it's so large and traffic moves slowly.
If you opt to rent a decent size SUV or van instead of an RV, don't despair rental cars in south new jersey of finding vacancies in the Parks. You just have to be persistent. People do make reservations a year in advance. Then they discover they can't make the trip and release those spots. Calling often, more frequently as the time gets closer, will often result in snagging one of those. The same applies to the campgrounds.
Depending on which Parks you want to visit, Vegas may or may not be your best bet. For Yellowstone one time we flew into Billings and drove the Beartooth into the Park. Another trip we flew to Salt Lake City and headed east to Arches, then hit Monument Valley, the south rim of the Grand Canyon, Bryce, Zion, etc in a big loop.
My best advice is to zero in on what Parks you want to visit - while looking at a map so you keep them somewhat "clustered" and go from there. So many wonderful ones. It's hard to choose. It's also hard to go wrong.
If cost is an issue, consider camping. Cheap equipment is available at any K-Mart, Sports rental cars in south new jersey Authority, etc. The cost will be recoup in ten days. But it assumes that one is willing to cook and that the kids will help in setting up and breaking up camp. Donate the equipment to Goodwill at the end of the trip.