For the kids albums I usually do double page spreads and stick to 1 theme for that , but the whole album is all very different in total.
The only time I stick to a theme for an entire album, is when its a pressie ( ie An aunt loves purple, so did only shades of purple for her album)

You've got to think too, it will be for more than a year, IYKWIM, and say Easter stickers,you dont want to have to use the suzy zoo ones more than once. You will see ideas you absolutely love, and it wont match the others, so yeah I reckon take each page as it comes!!!