As far as my own experiments, I have one involving St. Germain, Lillet Blanc, and calvados. Lillet and calvados are an unexpectedly good combination, as I found out one time at Absinthe, when a cocktail based on that mix was on the specials menu. St. Germain and dry vermouth are also a great combination (my own discovery, which I used in my Shanghai 1929), and since Lillet is another herbal fortified white wine (albeit sweeter, and with quinine), I figured the same principle may apply. Attempts so far, based on 1/2 oz each Lillet and St. Germain, and 1 oz calvados, have been promising but aren't there yet. My first try added a splash of Stirrings Blood Orange Bitters, and was drinkable but nothing special. My second replaced that with a dash of Angostura bitters instead, and (inspired by the recipe for the Gemini, though decided on before actually trying to make that drink) topped with prosecco. The prosecco was a good match, but something still was a little off. The floral aspect of the St. Germain was buried. Tonight I tried it again, but this time with a splash of orange flower water, on the reasoning that that had thrown off the balance of a prototype of the Shanghai 1929 too far towards the floral side. It didn't make much difference on this though. I'm going to have to fiddle with proportions. Next I'll try bumping the St. Germain up to 3/4 oz and see what happens; I hope it isn't too sweet.
Also tried tonight: a preliminary experiment with green Chartreuse and Cynar. Equal parts mixed was a little harsh: adding one part Lillet as a buffer calmed things down. I tried adding 1 oz gin (Hendrick's) and filling with cucumber Dry Soda. That was a poor choice: the cucumber soda overpowered everything. It didn't taste bad, but it tasted pretty much like cucumber soda with a little spiciness in the background. I think I may try the Chartreuse/Lillet/Cynar triad with tonic water; I'm not sure about the gin as the base spirit either. On the plus side, the resulting drink was a really unusual shade of yellow, like it couldn't tell whether it wanted to be amber or a slightly greenish hue.
EDIT: Tried 3/4 oz St. Germain, and Peychaud's bitters instead of Angostura. The extra 3/4 did not make it too sweet. I may be just about done fiddling. Probably not an instant classic, but a good drink nonetheless.