I personally think that the Beolab 5000 system, along with the stereo spatial width control, Beovox 5000 Beovox 2500 is a great suggestion, I wish I could get my hands on the BeoThoren turntable, but I can compensate myself by having the Beogram 3000 Acoustical, which might even be rarer.
I'd also strongly recommend a reel to reel machine with this system, probably the Beocord 2000 delux, which I unfortunately don't have, so I make do with a couple of Beocord 2400 - one 2+4 track one 4 track only.
This system is not something you tend to move around the house much!
The next one would have to be the Beogram 4000 along with a Beomaster 4400 and perhaps the speakers need to be Beovox M100 and although its a slight cheat, the cassette machine probably should be a Beocord 2400, I've not been able to get the speakers but the Beovox 5700 make a very suitable alternative.
I think a goodly collection from the Beomaster 3000 derived units is something for a collector to aim for, there are quite a few to choose from.Thise discrete amps seem to have a better sound than the stylish 1900-4500 range.
I think that only in stylistic terms, something from the Beomaster 1900 range is something a collector should have, plenty of alternatives here from the 1900 right on through to the Beosystem 4500, I would plump for the Beosystem 3500, decent cd player, decent cassette, relatively cheap compared to the 4500.
Beosystem 8000 with Beocord 9000 along with the huge Beovox M150 would be rather nice and very symbolic of B&O style.
Something from the Beomaster 5000 styled stuff, I think probably the Beosystem 6500 or 7000 since the Beolab Pentas are also high on the list.
The Beosound 9000 is very much a B&O icon and has been widely copied, very badly usually, this should be coupled with the Beolab 1s
I'm not too sure about the BeoCenter 2, I do think a good Beocentre 3500 is an essential. the Beocentre 2500 is also an essential - the sliding glass doors were such a feature back when it first came out and something that got the punters interested, especially the way it broke free of certain physical constraints by having the power amp section in the speakers and so creating a differant concept.
In terms of tvs, you'd have to include the Avant or Beocentre 1 there are older tvs that also were striking such as the LX series and some of the earlier still delta tubed tvs which still have fantatic pictures.
A set of the soldiers is essential, perhaps a Beotime, a portable radio or two, mugs and other bits and bobs.
Other stuff has already been mentioned.