I suggest going for self catering there are usually some large houses available at Dalnabay and large chalets/lodges at Dalraddy Hol Park
Also try SYHA at Glenmore - some family rooms available
Come with TREKnTRAIL for a memorable and enjoyable outdoor experience walking or mountain biking in the wonderful Cairngorms National Park near Aviemore.
www.trekntrail.co.uk