Share a room

Crowd the clan into one room rather than renting two

If you don't need the privacy, don't rent a separate room for the kids, as it will cost twice as much.

An extra bed in your room will cost, at most, 35% more. Cots and cribs cost even less (sometimes nothing, if the kids are young enough).

Triple or quads (rooms with three or four regular beds already in them) are more expensive than a double room, but less expensive than one double plus one single, or two doubles, respectively.

You get my drift.

If you find you do need a bit more privacy on occasion, ask if a hotel has family suites, where two separate rooms share a common door to the hall, or there are two bedrooms within the guest quarters.

(And, unlike in the States, you cannot really sneak four people into a room for two without paying for them. You pay by the head in Britain, not by the room.)

Snuggle up: Double beds cost less than two singles

This is a rule of thumb slowly fading from the European lodging scene, but still in some hotels you will find that a room with a "double bed" (double or queen) will cost a bit less than one with two single beds, mainly because they have to wash only one set of sheets.

Bonus hint: if the seam in the middle bothers you or the gap begins to widen as the cots underneath slowly slide away from one another under your weight, unmake the bed and rotate the pair of mattresses 90 degrees to that the seam is now horizontal.

Consider a larger living space

A family can actually often make out better renting an apartment for a few days, staying in a residence hotel (serviced apartment), or even renting a cottage or villa (though those usually requrie stays of a week).

This will give them the extra space and beds (or, you know, sofas) to house everyone comfortably while costing less than two hotel rooms—heck, sometimes less than one hotel room.