Pembo, we've been to Anna Maria a few times, but haven't stayed in Holmes Beach, that area is more "touristy" from what I recall. The northern part of the island is very nice and more residential (quieter).
This summer we stayed at a place called Anna Maria Beach Cottages and it was wonderful, but they get booked early. If you'd like to know anything else about this place, just pm me.
There is also another place called Bungalow Beach Resort in Bradenton Beach (North of H.B.), and that was nice, too. Wherever you decide to stay, just make sure that it's on the ocean side. You really don't want to cross the street to get to the beach, especially with young children. The traffic along the main road is dangerous.
You may want to pm Bet Snyder, she is VERY familiar with Anna Maria island and the one that first told me about it.