I have a Pro Flickr account. It is cool to store photos and receive feedback to your photos.
But for sharing with family, I can honestly say it is pathetic. Scrolling thru pictures is slow, your family can't download all the photos to an album, and the general interface is quite complicated. (Not for me, but my family has told me that they don't like the Flickr webpage).
So I've been searching around, and I think I'll go for MobileMe, which I had before and my family enjoyed using it much more. It is more polished, even tho it is also slow to load photos, it has a much better navigation system. And your family can download all the album, and also upload photos to the album.
It's expensive if you use it only for the photos, but if you have an iPhone, a Mac and an iPad, it starts making sense to get it.