Lance,
Clubs are a great place to get fair value input on specific machines. I would suggest posting year and model information with a few representative photos on club websites for each of the three machines. The Morgan Three Wheeler club of course (mwtc.co.uk) for the trike, the U.S. Lotus club for the 7: Lotus Ltd (lotusltd.com) and for the Triumph I might suggest the U.S. Triumph Motorcycle club (tomcc.org) though others may have additional suggestions for that one. All three machines could have international interest, though selling in the U.S. would likely be the easiest for the family.
There will be lots of debate and input from the club forums, so be prepared to sort through that, but it should provide a reasonable range of values. Then there is the question of best venue to sell. Again the club input should be useful there.
