My FAVORITE, FAVORITE, FAVORITE offsite place to stay is Staybridge Suites Lake Buena Vista.
Very clean. Awesome rooms. Nice pool. Laundry room is clean and useful. Location is excellent (1 mile from gate near DTD). Breakfast is excellent - Includes: multiple cereals, eggs, make-your-own waffle station, bacon or sausage, muffins, white or wheat bread, some fruit, multiple types of juice or coffee. The breakfast staff is friendly and keeps everything very well stocked.
You can get a 2 bedroom for $99 sometimes - depending on time of year, etc. And with that breakfast, for 6 people you'll be saving $50 a day.