We are just finishing up our own road trip from MN (my wife and I and three children), and we were on site from the 24th thru 29th of June, not exclusively for Disney stuff. We stayed at the Embassy Suites South on Harbor Blvd, and it worked rather well for us. The buses to the DLR leave every 1/2 hour, and if you plan it right and get up in time, the first bus out was never full (7:15 am departure). That got us on site 1/2 hour before either park opened. Also, the resort was letting all of the guests in early, apparently so that they could assemble the Fastpass line for RSR, so there did not seem to be much benefit to the resort guests who had the early entry. I stood in that Fastpass line two mornings, and it worked really well, as I let my wife and kids go enjoy a few other rides while I stood in line and waited.
Best of luck to you!