That is a very busy time at DL. If the budget can stretch for onsite, I'd go for it. EMH is great during summer, just be there when it starts, don't be late!
Side thought: have you thought about 3 day tickets? The parks should be running full hours (8am to midnight DL) making it easier to take advantage of the 3rd day even if you only have a half a day to use it can be worth it! Personally we get a lot more out of half a day in the parks than exploring downtown Disney. There's just not much to explore to us, it's some shops (which you can see online ahead of time if you're interested in any of them) and restaurants that as expensive as those inside the parks! (Exception: Earl of Sandwich, if you're looking for bang-for-your-buck food go there, close to DLH too! Also there is a Starbucks, and Haagen Dazs if you get an ice cream craving.) Does your crew swim? DLH has those monorail water slides, and you may really want an afternoon break each day during the heat of the afternoon (July can be really hot) so if a break is not in your plan I'd consider making space for one.