I am interested to know if there are any suburbs losing people
Yes. 2005 numbers released by the Washington State goverment show that Seattle suburbs such as Bellevue, Kirkland, and Mercer Island are losing population, but the county still grew by 20,000 people over the last year.
However, it's not that families are leaving, it's that kids are graduating and leaving while their parents stay there and have no more kids. Those cities have no more land left to annex and therefore will have to wait for elderly couples to leave or die so a new family can replace them.
The Cleveland suburbs have been losing people since the 1980s.
