The 2 bedroom DVC tend to be the MOST expensive option. (And out of the DVC 2 bedrooms SSS and OKW have the least expensive 2 bedrooms on property. They are also the furthest away from the parks).
We have 4 kids and have done a few different things but most often it is more affordable to do 2 connecting rooms over renting the points or paying Disney for a 2 bedroom DVC. It would depend on the time of year that they are visiting and if they plan on eating in the entire time which might help supplement the amount more that you pay.
AOA family suite is always the least expensive option for 6. There are also suites that sleep 6 at Coronado Springs, WL, & BWI, however they are really small. The one at WL & BWI are the deluxe rooms and only have one bathroom and 2 queens with a pull out sofa, however one nice perk to these rooms is that they come with concierge. I would not call them affordable though.
Connecting rooms are never guaranteed to be connecting which is something to think about as well, however, we have gotten them every time we have asked but I am always a mess the month before we leave worrying about what I will do if they are not!
Doing that right now actually about our trip in Feb actually!
If you want any specifics about any of the options feel free to PM me. I think I have researched every way possible at DL and WDW to fit 6 people into a room/rooms.
Good luck to your friends.