For a family holiday, you really won't better the Aviemore area. There's tons to do - including all sorts of "adventure" sports, the walking etc. You're also within fairly easy reach of Loch Ness, Culloden (great new visitor centre), the distilleries and some great beaches up at Findhorn etc. You'll also find some indoor stuff for the inevitable inclement weather. There's a leisure pool in Aviemore, a much better one in Inverness, an indoor playhouse / crazy golf course at Coylumbridge, a climbing wall etc.
We're up there quite a lot and had a two-week holiday last July. My wife reckons it was amongst the very best holidays ever.
You'll find lots of accommodation at visitscotland. Be aware though that there's a quite an international "push" on tourism this year and that things are booking up early.
As for the "midge", it's generally not so bad in the Speyside area as in the West, although places right on the sea in the West are usually OK due to the onshore breeze. Truth is, if you're indoors in the evenings, if it's windy or if it's sunny, you'll not really notice them. There are various recommendations for repellents etc. Strong deet is sur to work, though it can melt plastics (think of those Oakleys!). Many swear by Avon Skin So Soft Dry Oil Body Lotion. Don't laugh. While it doesn't actually repel them, they tend to drown in it when they land on you. Be aware though that you'll smell like an old lady..
I could go on for ages. If you want any more help, feel free to PM me.