From Dallas/McKinney, you can drive a few hours to see a large variety of wonderful sights. You will enjoy sightseeing from the comfort of your RV and easily find a park or campsite to stay in overnight. Right in McKinney you will find the Heard Natural Science Museum, one of the most visited attractions in McKinney. It features hiking trails, wetlands, indoor and outdoor exhibits, a native plant garden, and a wildlife sanctuary. Also, while in McKinney, visit the Collin County History Museum, which is a historical resource that preserves the history of McKinney and Texas as a whole. It is named after Collin McKinney, a revolutionary politician from Texas. He was among the people who instigated the Texas Revolution in 1835.
In Dallas proper, is the Dallas Heritage Village at Old City Park. Drive a bit farther west and you come to Fort Worth, where there are tons of attractions and more things to see and do. And if you should be more adventurous, keep driving about 3 hours west on I-20 to go to Abilene.
Abilene is home to the Abilene Zoo, which has more than 1,000 animals, including giraffes, white tigers, and snakes. The 19th century Fort Phantom Hill is here too, and is part of the Texas Forts Trail, connecting various West Texas frontier landmarks.