If it was me, I would tailor the party to suit my one year old and not worry too much about the older kids. After all, it is not a party for older children, it is a first birthday party and it should be expected that therefore the focus is on the birthday girl. Don't go to the expense of hiring things just for the sake of the older kids - unless you really want to because your DD would enjoy it.

Otherwise I have found in the past that simple (and cheap) games like pass the parcel always go well - even the oldest kids will still want to play, and they can help the younger kids with it at the same time. Also something like a pinata would probably be popular. You can get the ones with ribbons attached, so that all the kids have to do is pull on the ribbons to break it open - a bit safer than bashing it with something!