I know I am biased but have you considered a cruise?
A ship like the Independence
http://www.beyondships.com/RCI-IOS-Profile.html" onclick="window.open(this.href);return false; sails out of Southampton, offers 5 star luxury and comfort superb food that you can eat when you want (24/7 if you wish) and you don't put weight on contrary to myth and you have all the entertainment you want.
Ice skating, surf simulator, rock climbing, cinemas, gym, pools (there are about 5 on board) whirlpools and there are clubs catered to look after the kids of all ages.
The best part is that you get to see different countries and it gives you a flavour of that coutry (we did Russia last time) and the perception of a counry going in by sea is so different to flying in.
And there are no queues, you wake up in a different country each day and no flying. Even check in is 5 star similar to business class lounge at the airport.
Last time we cruised on the Independence (which at the moment is the biggest out of the UK) we did 18 nights in the western Med. We did Lisbon (which on a shp is an experience coming out under the bridge) Gibralter, Monaco, Rome, Cadiz and 4 or 5 others ports of call and you get to spend a day in each port of call.
18 nights with a balcony cabin cost us under £1K. I could not do a fortnight in Spain for that and I would still have to buy my own food, hire a car etc. And remember everything is included. All you pay for is alcohol and branded soft drinks which are duty free anyway.
We did the Carribean in December a few years ago on the Carnival Glory. 27 degrees. 14 nights, including flights and a hire car for te first and last days, visiting Mexico, Belize, Honduras, Grand Bahama with a balcony cabin we did for £1100 each.
I am looking at the Pacific next year, 14 nights visiting the Hawaiian islands sailing back to Canada including return flights all inclusive? £1200.
Far east, Hong Kong, Singapore, Vietnam, China etc is even cheaper....
If you have not cruised before, it is worth trying, even with the kids. You may get hooked and it is not expensive in terms of what you get for your money and if you shop around there are deals to be done.
When we did the 18 nights in the Med, one couple with a cabin identical to ours paid £500 each as they were able to book at very short notice.
Just an idea.
I have done quite a few now, and I don't even consider other types of holiday anymore, we just decide what countries we would like to visit and which ships get us there.