The good thing about Heathrow's Plaza Premium Lounge is I will be never returning.
During my last trip I used a fair amount of airport lounges and the standards and costs vary drastically. I do think the use of a lounge is worth while if you have a few hours or longer to kill. The cost of food and drinks in the airport is on on your side we passing time. By the time you have had a few drinks and a bite to eat you are already well over the lounge entrance cost. The other plus side is they offer shower facilities which are monitored and kept clean.
The reality is if the airports are over priced mainly down to having a captive audience for a few hours or more and they are going to milk you. In most places it is hard enough to find a seat ad knowing you are going to be cramped up for a few hours in a plane finding somewhere comfortable and less crowded is not a bad idea. They have information screens up showing the boarding of flights so there is no need to worry about missing the flight.
All airports will have some type of lounge available for those with regular airline memberships plus those willing to pay cash for an entrance fee. The only way to find out if the lounge is value for money is to try it out and this unfortunately is where the hit and miss comes in. You will know fairly quickly if you have made the right choice.
Top of the list has to be the Gatwick Airport Public Lounge which at 32 GBP per person is not the cheapest, but it also offers a sun deck on the roof top. The food and drinks available were different to what I have seen else were and there was a wide selection covering for all tastes. The quality of food was restaurant par and we spent 4 hours ere waiting for our flight. What was consumed during this period far outweighed the cost of what it would have cost to remain in the airport restaurants.
They even ad a pancake maker which took a few minutes to make two small pancakes.
Oliver Tambo's Lounge (Johannesburg) I never visited the lounge on this trip
as I only had around 1 hour to kill before boarding so it would not have been worth the expense. This is the cheapest out of the lot being R250 per person which is around 12 GBP or $14 per person. The food and drinks on offer is varied and comparing what I have seen else were is actually good value.
Heathrow Terminal 5 this trip we had 8 hours to kill and the public cash lounge was the worst I have encountered so far. The price of 62 GBP per head was expensive ,but then we were there for 8 hours and the price was adjusted from the 37 GBP entrance fee. They look at your boarding pass to calculate the hours you will be staying. The food was sub standard and all the same and it was basically a poor standard of curry or nothing else. Not surprisingly the kitchen staff were all Indian and they are cooking food they know. Thee was very little effort shown in the food department and this you could see was a very profitable business as no one got fair value. I do think next time if I had 8 or more hours it would be more beneficial to find a local hotel and rest up than spending 135 GBP on noting great. Also having a shorter stopover would also help.
The other top lounges I would like to add and recommend are Charles de Gaul (Paris) and Dubai who were another step up for all of those mentioned above. These lounges offered sleeping chairs so you could fully stretch out and relax. Dubai even had smoothie bars along with the food and drinks that are normally available.