Priority Pass
I've been using PP for some time and find it very useful, particularly when there is a delay. However you need to be prepared to accept a wide variety of differing lounge standards. In some places its a seriously simplistic option, in others its really good. In the UK its generally simple lounges run by the resident handling company although there are some gems if you look for them. Most of the major airports get several options too. As far as DXB is concerned the lounge there is OK until its gets super busy, but then the whole of DXB suffers like that occasionally.
Where its really useful is that, whilst there are many lounge systems you can prebook, with PP you can just turn up if you suddenly find you've got a 4 hour wait instead of the hour you though you had. The main benefit for me really is that you end up somewhere mostly reasonable and with all your facilities, toilet, showers, wifi, snacks, etc in one place. A lot of the lounges also have a bag store so you can go wandering without lugging your cabin bag verywhere.
I tend not to use the facility for a stop of under 90 minutes or so unless the airport I am in is seriously naff!! From a financial point of view the £15 charge can soon be reduced dramatically when you consider the cost of coffee, snacks, papers, wifi, etc in the main part of the terminal. In some places 1 alcoholic drink, 2 coffees, a couple of sandwiches, a cake and wifi actually puts you in profit!!
There are several options when you purchase PP. Mine is the simplest and cheapest as my travelling varies widely from occasional to frenetic.
Its also very useful on the odd occasion you are travelling with a work colleague who you can seriously impress when you invite him to join you in the Business Lounge!!