Daysailer for two ... ?
I have not read back through this thread, so someone else may have chimed in with this earlier, but I am a fan of the Oday Daysailer, which ultimately was built by a number of other builders. These were reasonably well constructed, can be purchased in competitive condition for a very reasonable price and is still raced competitively in a lot of areas of the country and so hold their value quite well vs some of the newer designs that you have been considering. While not as high performance as a thistle or lightning, they are easy boats to sail and can handle a reasonably wide range of conditions. Most had integral outboard motor mounts (which may need rebuilding) and were pretty comfortable boats for a couple of peope to sail.
Another similar choice is the Sailstar Explorer.