Only you can decide if you'll regret it or not, that's purely subjective. If you've been for Thanksgiving, then 4th of July shouldn't really bother you...unless Thanksgiving bothered you. We've been to a lot of 4th of July weeks, including '15, '16 and will again for '17 and '18. MK on the 4th after 4pm is crazy. Don't think they closed in '16, I think they may have in '15 (but not sure). Either way, that's the only truly crazy busy time/place. The rest of the parks and the rest of the week are certainly busier than average, but manageable for sure...at least to us.