I've dialed in my carbonara recipe and technique pretty well, but this is the first time I've tried Amatriciana (I consider them Roman cousins as you're replacing the egg (yolk) with tomato, no offense to the residents of Amatrice). Used spaghettoni (secca) as I prefer it to buccatini. Pretty happy with the results, as were everyone I fed! Rough recipe to follow.

Slowly heat up pasta water as you trim the guanciale, slice into lardons, slowly render until just slightly crispy, but still meaty/chewy, remove from pan. Add tomatoes--I use passata, you can crush your own tomatoes. Season to taste, but keep in mind Pecorino Romano (and guanciale) is quite salty. I usually just add MSG and a LOT of pepper (freshly ground, preferably toasted ahead of time). Deglaze, turn heat to low, cover while the pasta cooks (about 10~12 min). Stir every once in a while. 

Cook the pasta--I don't salt the water, see Pecorino Romano remarks above, I do add MSG to the water. Cook the spaghettoni to instructions, minus 2 min. The sauce should cook about the same time as the pasta. I've seen much longer cook times, but around 12 min worked for me. 

Grate Pecorino Romano while the pasta and sauce are cooking. You can find weights and ratios all over the place, but I eyeball them, grate/add more if necessary. 

When the pasta is ready (minus 2 min), add to the sauce pan, don't be shy about getting pasta water in the mix, and reserve a cup of it on the side. Turn off heat while stirring, start adding the Pecorino while tossing/stirring the pasta, use pasta water as necessary. This part takes practice, but is more forgiving than carbonara or cacio e pepe, for which I'll use the pasta pot as a bain Marie. I found amatriciana didn't make the cheese curd or get stringy just tossing well, off heat.

Plate (I can never do the pasta ball thing...), add the guanciale, grate more Pecorino, pepper, eat while hot!

Notes and variations: I didn't remove any of the rendered fat, used way more of it than when I make carbonara and the sauce had a wonderful, porky flavor. Not the healthiest choice, obviously. You can also leave some of the guanciale in the sauce after adding the tomato, but I wanted all crispy on top of. If I'm ambitious, I'll also try (hand) crushing my own tomatoes, but passata is just easy (though I'll toast my peppercorns...). 

1st try at Spaghettoni all'Amatriciana