My $0.02 worth...
The highest rated resort in the TUG reviews is Brewster Green. I personally think BG is really nice, although somewhat dated. Some of my family members don't like the location, because the resort is somewhat secluded.
I agree with the above observations --- and I'm personally just fine with "somewhat secluded". Heaven knows there is precious little of
that amenity on Cape Cod during the summer months. Having once lived year round on lower Cape Cod for some years, I've seen most (...maybe even all, I'm not certain) timeshare facilities on the Cape at one time or another and I frankly don't think that you can possibly beat Brewster Green,
all things considered.
By "all things considered", I specifically mean having a decent sized condo with a full kitchen, decent proximity to CCNS beaches and trails, being far enough away from the congestion and traffic of "greater Hyannis", nearby access to the Cape Cod Bike Trail, numerous decent restaurants which aren't just crummy "tourist feed troughs", somewhat central location on the Cape, as well as good access to nearby Chatham and to other lower Cape towns such as Orleans, Wellfleet, Truro and Provincetown.
This is the Cape discussion point at which e.bram usually surfaces to tout the perceived virtues of a timeshare in Falmouth called Surfside. Its' "beach nearby" location notwithstanding, Falmouth (and ditto for Mashpee) is
not a part of Cape Cod where I would want to spend a whole week. To each their own, of course. YMMV.
All that being said, odds of "exchanging" into BG in August and getting
two 2BR units for the same week are basically
zero, no matter
what you might have to "trade".
As already mentioned by others above, a weekly house / cottage rental might be a more realistic and attainable (albeit considerably more expensive) option.
You surely (and understandably) won't want to spend a full week at any of the numerous "Cape Cod motels converted to timeshares" for a family reunion.
In any case, good luck with your quest; family vacation / reunion is a wonderful thing.