

Amaro is a very loose category of liqueurs. It’s spirits and/or wine infused with a variety of herbs and other flavors. It’s bitter and often very sweet at the same time, with a complex mix of other flavors. There really is so much variety it’s hard to narrow down, but a couple personal favorites are Cynar (very bitter), Montenegro (kind of sweet), and Amaro Nonino (well balanced).
Lots of good recommendations already.
I’ve only made Coquito with Appleton Estates, but that’s mostly because I have Appleton around during the holidays to make hot buttered rum for my wife’s family. The white rums that I’ve had and liked have been the Plantation and Rhum Barbancourt. Like others said, you probably won’t taste much of the rum.
I’ve never had a Godfather, but that sounds like a perfectly fine drink. I like Old Fashioneds and other drinks that follow the same bourbon plus a dash of something interesting format. I would bet that the drink will still mostly taste like whatever whiskey you use. Don’t bother chasing down something special or expensive, but I would go with something good. Also, you’ll still have the rest of the bottle to finish, so buy something you’ll drink. If you already have a preferred bourbon or whiskey, you’ll probably still like it in this drink. I would try something like Old Forester (100 proof), Four Roses, or Wild Turkey 101.
I have not had any amaretto apart from DiSorano, which I do not like.