For DD we invited all of our friends over for a big fall get together and when everyone had gotten there we asked everyone to come over for a second so we could say thanks for coming. At that point DH and I announced we were pregnant, it was a lot of fun to see their reactions in person as a big group esp since we were the first ones to have a kiddo.
To tell our parents we told them we had a belated anniversary present (for his parents) and for my mom we told her on my birthday. For both we got them sleepers that said baby on them and wrapped them up in a shirt box like any other gift. It took a second for them to get it but they were excited.
And I love the pic idea of the three of family together and plus sign = 4