Best route to and within Yellowstone from Nebraska

Cloud Driver gave you recommendations that in my mind is the way to go. If the early pioneer days and the Oregon trail interests you then the Hwy 26 is a gem. Great fun. The fact that you will have considerable needs of your RV, it would seem that Fishing Bridge CG is for you. Don't let the crowds worry you. It is always busy in the summer so take your patience with you and make meeting people part of the fun. Everyone there is engaged in the same endeavor you are, seeing some of the most amazing things on the planet. I hope you have a grand time.

Thanks for the tips, these are great! Unfortunately Madison doesn't have anything available for our size RV. I like Fishing Bridge's location but the reviews said it was crowded, no camp fires allowed and very limited on space outside your RV. We're traveling with MIL (who can't hike) and two teenagers so do plan to spend some time in the campground. Thanks again!

We have crossed Nebraska a number of times on trips west. We usually enter at Nebraska City and take route 2 to join I80 at Lincoln. West of Grand Island we move over to route 30 to get away from the heavy truck traffic on I80. Route 30 is a bit slower, but a much more relaxed drive. At Ogalalla we pick up route 26 all the way to I25 in Wyoming. Route 26 follows the Oregon Trail past Chimney Rock, Scotts Bluff, Fort Laramie and the wagon ruts at Guernsey. Fort Laramie and the wagon ruts are well worth a stop. At Casper we pick up route 20/26 to Shoshoni then route 20 trough the Wind River canyon to Thermopolis. From Thermopolis route 120 will take you to Cody for the east entrance of Yellowstone. This route has no mountain driving until the east entrance.

Regarding your campground question, Fishing Bridge is the only campground inside the park with hookups. If you need hookups, that's your best bet. If you can get along dry camping then my suggestion would be Madison campground on the west side of the lower loop. The great majority of the thermal features are between Madison and Old Faithful, plus it isn't a long drive to the Yellowstone Canyon. IMO Grant Village is too far from the action.

Thank you for the link and info, very helpful!!

Summer before last, took Neb. Hwy 2 all the way to Hwy 20. Good scenery, almost no traffic. Several towns along the way have city-operated campgrounds that are clean and inexpensive.

To cross Wyoming, it depends on which Yellowstone entrance you choose. We went through Gillette and Cody, Wyo., because we wanted to visit the Buffalo Bill Museum in Cody. I recall good roads along that route. We also visited Badlands NP and Devils Tower along the way. But if you want just to go straight to Yellowstone then the road through Casper would be faster.

Here is an article which describes the various routes into Yellowstone. I strongly recommend that you scroll down to the section on the Bighorn Mountains. They are not RV friendly and can be dangerous.