HI Paul, and welcome
Friday they do run up the hill, but they aren't always timed and some of the 'stars' wont be there. It's certainly quieter [and cheaper
] on the Friday due to the lack of 'stars', so access to the cars and photo opportunitys are easier to come by.
I usually do Thursday and Friday, however this year I intend to do all 4 days
seeing as its going to be a special one
We [as in other AF.com F1 nuts] normally try for a meet up on the Friday, either for a Beer or next to a Mclaren to have a chat, so if you are up for it too, send me a PM and we'll take itt from there