I don't remember what we had in the house when I was a child - must've been some pics as we always bought school photos.
We don't have huge numbers of photos, most are in the living room, and all bar one of those features DD (the one that doesn't is me with both my grandmothers on my graduation day). Hang on - there's a wedding pic as well. Three school photos of her, one whole school pic (I love this, 420 kids, it's like real-life Where's Wally), couple from a session done when she was 9mo, nursery pic (cutest thing ever) and snaps. All on the bookcases.
There are two on the stairs of DD from the back, both aged 2 or 3, one watering a plant and one on the beach with my parents. DH thinks they're weird but I like that they're kind of anonymous.
Teeny tiny one on a shelf in the dining room, my dad and this brothers aged about 3, 6 and 9; it was the only thing I took from my grandmother's house after she died.
That's it - DH thinks we should have fewer when we come to sell the house, but I don't agree. Is it ever tacky? Well, photos don't look so nice when they're loads of stiff school photos with bad haircuts in cheap frames against generally tired decor, but that's not just the photos. And the in-laws do have a canvas-effect but framed BIG version of the everyone photo from our wedding that I find a little scary ... mostly I like them, especially in other people's houses, and even more especially when we know them via their youngest child only - love those pics of current teenagers as squidgy babies and toddlers!