In PUNCH there was an interesting article about Amari that are made in the US. In that list I've tried Margerum amaro, which is closer to a sweet vermouth with a bitter edge than an amaro per se but is delicious nonetheless. Also Fernet Francisco that I mentioned already and recommend. Lastly I had a chance to try St. George Bruto Americano last week. I had it on ice and it is very intensely bitter, less sweet than Campari, and with much less orange. With its very long gentian finish, it reminded me more of Suze. I was told that it works great in a Negroni!