The most obvious omission from your list of nice places for a weekend break has to be Paris. Loads to do and see, with great food and wine ;-)
Alternatively, why not spend some time in Belgium? If you're in range of Stansted (or Glasgow), Ryanair have dirt cheap flights to Charleroi. From there, you can travel to anywhere in Belgium for just �21 (�14) return. (Go to the airport ticket desk and buy 'bulk tickets'. These cover the 10 minute bus journey to Charleroi Sud rail station, plus onbound rail travel to any station in the country). Bruges is a delightful city and a great base for exploring. (Ostend is less than 15 minutes away by train).
The Italian Riviera is delightful and easy to access. Just take a cheap flight to Genoa, then a cheap bus to the rail station and an equally cheap rail trip along the coast to somewhere like Rapallo. (It's a delightful town and, once again, a great base for exploring by using the frequent, cheap train services).
Those three suggestions are based on places I've visited myself and which I know you'll enjoy. One place I've yet to try is Marrakesh. Ryanair fly there from Luton and it should certainly be 'different'.
Chris