Given you mention some of your party are big Epcot fans, and some are big DHS fans, Boardwalk is probably your best overall choice. Walkable access to both parks, optionally boat access to both parks if you don't want to walk, and Skyliner access to DHS just to throw in another option. In the event of rain/lightning when the boats and Skyliner shut down, they do run busses to both parks...so there's always a non-walking option.
Boardwalk's dining options are all along the boardwalk, except the coffee shop - you have interior seating restaurants - Cake Bake Shop, Trattoria Al Forno, and Flying Fish, and you have exterior seating for the pizza window, Boardwalk deli, and Corn Dog stand. Of course, you can take a short walk to Beach Club, Yacht Club, Swan, Dolphin, and Swan Reserve which gives you all of those additional food options, plus you can take the Skyliner to Riviera, Caribbean Beach, or Pop for even more food options. And with Epcot being right there, if you have Park Hopper tickets, you can walk into World Showcase anytime to grab all the food options in Epcot, and including Food & Wine booths.
Boardwalk is my home resort, so I'm there a lot. When I'm in less of a rush to get to Magic Kingdom, I'll sometimes use alternate methods to get there instead of hopping the MK bus at Boardwalk. For example, I've taken a lovely morning stroll over to DHS - the first thing you hit before getting to the park is the bus stop - and hopped an empty bus to Contemporary (everyone's heading TO DHS that time in the morning, and no one is heading the other way)...and then walked over to MK from there. Same goes for Wilderness Lodge, Polynesian, and Grand Floridian busses from DHS - you can hop any of them, do a little resort walk-through, then hop their boats to MK. It's not faster getting there - probably longer overall, but so much more relaxing to be on an empty bus and some short walks vs being on a packed, standing-room-only bus.
As for August in Florida...yeah, it's hot and humid. Be ready for that. Though I don't see too much problem with walking into the parks in the mornings or back in the evenings, considering your going to be spending the entire day walking around the parks in that heat. You can dive into AC spaces whenever you can, but you will be hot and sweating at some point anyway, no way to avoid it. I live in S Florida, so for me, it's an easy decision to go to Disney in the summer, because my choice is to be hot and sweating at home, or hot and sweating at Disney, and the latter sounds better! It's extremely rare for Florida in the summertime to have full rain-out days, where lightning and rain do not stop and boats and Skyliner are shut down all day. Florida summer rains usually build in the mid-afternoon, so mornings are usually clear, showers pop up in the afternoon usually passing through for an intense 15-30 minutes, then pass...another might roll through in another hour or two. Lighting gets really active, some rides and transportation shuts down, and 30 minutes later, reopen.
You can never rule out a hurricane risk, though August is not typically when Florida has experienced the most hurricane activity. Florida's highest risk time for tropical activity is the end of August and most of September, with October waning but still a risk. June, July, and most of August are less frequent for hurricanes in FL, and late October to November are fairly rare. Most hurricanes that strike Florida don't make their way through Orlando...since I've been going in 1971, there have been 6 that did some damage in the Orlando area - one in 2004 (Charley), two made it there in 2005 (Frances and Jeanne), another in 2017 (Irma), 1 in 2022 (Ian), and one in 2024 (Milton). Most of them were not direct eye hits on Orlando, and none hit Orlando at stronger than Cat 1.
