As mentioned previously luxury can be measured in many ways. I feel having a clean comfortable bed with parking in a very popular city a luxury as limited time often means missing out on something if you are having to travel into the action from the outskirts all because the hotel (albeit luxurious) of choice is located as such.
I have been using Travelodge frequently when visiting London as they are often located close to a rail station or central to my plans. I can not sing their praises enough. Cheap accommodation with the certainity of getting crisp white linen, a comfortable bed, shower with toiletries, a tv, coffee making facilities and hanging space. Always friendly welcoming staff and usually the option of breakfast, other meals and a bar.
I can vouch for Travelodge at Egham, Waterloo, Southwark, Newcastle Waterfront and Stratford upon Avon and looking forward to the new Marlow in the summer.