There have been several threads that discuss the various issues of a family of 6 and lodging (I posted one myself!). I have four children currently ages 6, 7, 9, 10. We always stay in one room when we visit family and it is do-able. We let the hotel know and don't hide it from them. Some won't allow it due to fire code. Others will, especially if the kids are young or business is low. For our upcoming WDW trip, we have ressies at HIFS w/a Kidsuite that sleeps 6. No, it's not a Disney on-site resort and we'll miss out there, but as you said--how much time do you spend in your room?
Here's the deal:
1. Legally (fire codes, safety, etc) the hotel isn't supposed to go above occupancy limit which is usually 4.
2. There are very few on-site resorts that allow a family of 6 to stay in one room (I find the ones available are outside my budget --even Fort Wilderness since we don't have camping gear and would have to buy that!!)
3. That left my family with staying on-site and get adjoining rooms (double the cost) or staying on-site and lying, hoping not to get caught (our consciences and beliefs won't allow us to do this, even though my budget screams for it!
)
4. So we looked off-site and got HIFS at a good rate.
That's how I got where I am. Hope it helps.
P.S. I agree with the others who commented about sharing a bathroom. If you've come from a multi-bathroom home, you can't imagine sharing, but I also grew up sharing one bathroom (family of 5) and never thought anything of it.