Fran- Caroline is correct and GA isn’t great in Monaco. Its basically the hill that goes up from la Ras Cas to the royal castle. Its very steep, crowded and doesn’t seem to be many facilities there. We went and saw the royal castle I think Tuesday before the race and people had set up (and chained in) chairs. It may well be the only theft that takes place in Monaco to steal ones GA seat…. unless you go into certain restaurants or night clubs.
Monaco is great so if you cant afford a grandstand try the GA and see how it is or maybe try another. From your list above I haven’t been to Germany or Belgium (My next one I hope) but have been to Barcelona. Between T1 & T2 through to T4 or T5 (where the Mercs crashed in 2016) there is a big hill with great views, heaps of food and amenities around that would be great to watch from and a great atmosphere as well. And being a proper circuit viewing is great, although in the right spot at Monaco you can see so much of the track.