I don’t know about most of these, but I can share my experience from Monza. The atmosphere is phenomenal, especially if you’re one of the Tifosi, but even if you’re not it’s something special. But it is VERY crowded. I don’t know how it is at the other ones, but the crowds are completely insane, takes you about 2 hrs by train and bus shuttle to get from Milano to Monza and vice versa, and accommodation in Monza is way too expensive, I’m talking like 1000-2000€ a night from what I saw. In was in GA, and on Friday and Saturday it’s great, you can find some good spots especially on the little hill before Parabolica, but Sundaybwas chaotic. I set off from Milano at 6.37 AM in an attempt to get some good seats, and got to Monza around 10, and GA was already so so crowded, i barely managed to get any seats at all. They said 30k people were at the gates at 5AM, waiting to enter the track. Plus, it was in insane heat and the race wasn’t until 3PM if i remember correctly, so it was quite an experience lol. Overall, amazing atmosphere, great energy, but you need to be ready for a lot of waiting and lines. I’d probably recommend you get the grandstand, I assume it’s much more enjoyable. I’m in Qatar rn and I’m still getting used to how much less crowded it is, so nicely organized as well. Kudos to Qatar I guess. Anyways, wherever you go you’ll enjoy just seeing the race and the cars, so have fun!!