I am going to go against the grain here and say keep the week starting June 25th. Only because, assuming you are staying for 7 nights, that would give you a check-out date of July 2nd. I would do anything in the world to avoid the madness of July 4th weekend in WDW, ESPECIALLY since it’s an actual Saturday. Temperature wise you’re not going to notice a difference BUT add in the July 4th crowds WITH the heat and in my opinion it’s just a nightmare.
I was in WDW only ONCE in my life during July 4th and I’d never do it again [notice my trip dates below :laugh:], the park got to capacity & at one point they were ONLY allowing admittance to resort guests. I was a resort guest but once I got inside I wanted to walk right back out.
I know $300 is a good savings but for me it would have to be AT LEAST over $500 in saving for me to stay during July 4th.
Just my opinion.