Whenever I have flown from thge UK to Europe or the States I have always put 1 suitcase in the hold. Do the airlines allow you to put 2 suitcases or bags in the hold as long as they both do not exceed the 20kilos,or is only 1 suitcase or bag allowed in the hold? We are thinking of flying from the UK to the States with Virgin Airlines.
Some airlines, e.g. Ryanair, like you to take as many bags as possible because they charge a fee for every item carried, so more bags means more money for them ;-)
PS: I note that your question seems to assume that all airlines allow a maximum baggage weight of 20Kg. This is not so. Both BA and Virgin allow a maximum weight of 23Kg per bag, for each of the two (or three) permitted bags. Ryanair only allow a total of 15Kg for all bags carried in the hold
Chris
(PPS: A slight correction to the above. On BA European flights, some travellers are restricted to a single bag, depending upon the class of travel)
if travelling to the US the weight allowance is much more than 20kgs, as I do lots of shopping I put one bag inside another bag for the hold, coming back I sometimes have 3 bags for the hold, as long as it does not exceed their generous baggage allowance it will be okay. Europe I dont know, but if your ticket actually states 1 bag thats what they mean, I find the cheaper the ticket the less baggage allowance as a rule.