We have 12 year old twins and a 4 year old, all boys, so know what you mean about keeping them entertained. We wanted to start caravanning to get the kids away from the TV and computer games etc but, I'm ashamed to say, we always take the TV, playstation and DVDs. It just makes life a bit easier when setting up and packing away not to mention when the weather is bad. I always go on eBay a few weeeks before we go away and buy a couple of cheap DVDs or playstation games to produce for those 'I'm bored' moments.
Really enjoying it though, only 12 more sleeps until we go to Brighton for our main fortnight. Hope the weather picks up or the playstation will be overheating!
Going to Longleat at October half term and heard that it's excellent. Friends of ours reckon their kids were thoroughly entertained for about 4 days just visiting the house, grounds and other attractions. If our 3 say their bored there, we're going to feed them to the lions!