I think there is an uptapped market for reliable bus transportation to WDW from resort hotels...lol.
If DH had experienced problems with WDW buses, then you don't want to depend on the offsite buses. Check out the transportation board, you may find some more info there. The trips are generally a few in the morning, a few at night... and maybe one during the midday. And, if the shuttle is "free"/included in your room rate, you probably will be stopping at more than one property.
You might consider staying offsite in a condo, it is a very economical way to stay. Lots of space, a full kitchen and very comparably priced to moderate hotels offsite. A recent poster reported staying at a new resort, Seven Dwarfs Lane for $499 per week for a 4bed/3bath townhome. check out
www.vrbo.com, general nightly rates are $69 - $89 per night. (Once you get used to the space in a condo or villa, you never want to stay in a regular hotel room again for more than 2 nights...lol) Of if you would like to go higher end, then look at Windsor Hills, the resort is beautiful and the pool is much nicer than the WDW moderate resorts. I'd suspect that summer rates at WH are in the $120-$160 per night range though.
Yes, you'll have to rent a car, but you can find good deals on rentals too. You can get an econo car for about $165 a week with taxes (plus $10 to park at Disney per day) but still an over all good value for all the space. You could also take cabs, about $20-$25 one way to the parks if you just don't want to drive.
Good luck!
Lisa