Delta is similar to UA in that they award miles based on the price of your ticket (for general members, UA awards 5 miles per dollar spent, less taxes). AA still awards miles based on distance flown (my current Scandinavia trip will bring in around 25,000 miles on a $700 fare), but they've announced they're going in the same direction as UA sometime in the second half of the year, and it's anyone's guess what that date is.

I'd look at Alaska which has a lot of partners (BA, AA, DL, CX) and see if they might work for you. I'm not up on programs outside the U.S. to really comment on those as alternatives.

There's no way to pool miles from 3 different family members. I know BA offers family accounts, but don't think any U.S. carriers offer that.