Caligula, youth hostelling works out really well for us. I like to take my boys away to a youth hostel for a few nights 2 or 3 times a year - just me and them. We stay in a family room. I find the hostels really safe, spacious and friendly places. There are few things children can damage, and there's usually a nice big garden is attached. My sons normally find other children to pal up with and the parents (many come with just a mum or a dad) are almost always nice people.
If you are on a budget Youth Hostels work really well:
They do not charge more in high season. And they may offer discounts if they have lots of spare rooms. This is a great plus in the summer holidays. The three of us had a family room at the Broadstairs Youth Hostel for £25.00 a night during mid August last year.
OK, I know a Travelodge can be about as cheap, but with a YHA you also get the use of self catering facilities, so you do not have to eat out all the time, and for me (two growing boys with big appetites) this is a Very Good Thing.
The locations (near city centres and places of interest, not just off the motorway) are a real plus as well.
This year, I am considering taking my sons youth hostelling in Europe. Looking at the internatial youth hostel website, European prices do not go up in the summer either, so there could be some real bargain holidays out there.