My family did exactly that, a week at Universal, SeaWorld and Busch Gardens.
But I take your point, I don't have any personal friends or relatives who've done it.
Most of my friends and relatives who have gone to Orlando did the following:
Booked a really big, expensive, first-time-ever trip to Orlando visiting only WDW parks and usually staying only at onsite hotels and eating only at WDW.
Went at a busy time of the year.
Had a fairly lousy time and complained about the crowds, the transportation, the cost and the value for money ... and vowed, "never again".
I'm not saying that the lesson is to avoid Disney and go to Universal instead, I'm just saying that accepting the proposal of a "Disney vacation" where you basically sign on the dotted line and let Disney plan everything for you is often not a very satisfying experience. If you take charge of planning your own vacation and assessing the needs/desires and budget of your family, you will very often come up with a "split vacation" between WDW and the other parks, and you may cut WDW out the picture entirely, especially if your kids are over 12 and not particularly smitten by princesses. Or at the very least, they will practically insist on going to see Harry Potter for part of their trip (like mine did).