I have a reasonably rapid GS, should I go faster Ferrari as a third car or something more regal? I am also leaning towards an XJS or a Jensen Interceptor.
I have had a normal GS Coupé, a GS Spyder and currently have a GS MCV.
I had a Jensen Interceptor a long time ago and I would definitely have another but beware cars that are shiny on top as they do have a metal chassis underneath and one chassis tube is used as an additional vacuum reservoir for the brakes so they are even more important than normal. I would go for an Interceptor II which has the 6.3 hemi which is more powerful than the 7.2 in the Mk III which is emissions strangulated (some early MkIII do have the 6.3) or an Interceptor SP.
I love the XJ-S, I own a vey early V12 manual with all the early features. Not had the chance to use it much but it is an awesome car. A good XJ-S is a fantastic car. Worth remembering the pre HE cars are more powerful than the HE cars but were less well protected rust wise.
Bentley Turbo R is also a great car, go for one with the gear selector on the central console (as opposed to on the steering column) as there are a lot of worthwhile improvements that go along with that change. Look for a car with an interesting spec it will make it easier to sell in the future. However if you really want something regal I would go for the Rolls-Royce version, they are much rarer than the Bentley and much better if it is regal you want. If you want the performance of the Turbo R then look for a Flying Spur which is basically a Rolls-Royce badged Turbo R, supposedly a limited run of 50 cars but in reality nearly 3 times that were made (they re-used the same Limited Edition No in different markets in some cases three times over!). Other than that a well specified Silver Spur (or Spirit) is still a lovely thing to drive. Again the more special features the better. I own a Silver Spur II Mulliner Park Ward edition, it has cocktail cabinets, a humidor, jewellery box, silver inlay in the mirror matched American flame walnut etc etc and it is a lovely place to be. Definitely the answer if you decide 'Regal' is what you want.
Hope that is of some help.