Silverstone once; hated it. Camped overnight, was there queueing up at the chain-link fence at Copse super early. Stood in the cold and rain all day, by the time the race started we were swamped with other fans and couldn't see a thing.
Spa several times; love it. Have watched the race from various places, Eue Rouge, Kemmel, Les Combes, Malmedy. Great views from the steeply banked slopes above Pouhon. Marvellous atmosphere.
Hungaroring; okay circuit to spectate at, very quick access to and from Budapest which is a great place. Great Irish bar opposite the West End station was really rocking when Eddie Irvine's sister brought his 2nd place trophy back after the race.
Hockenheimring; good for spectating in the stadium complex. Awful food. The time I was there our grandstand was facing the sun - summers in Germany can be hot - I've never been so hot in my life, and that includes years working in the Gulf, I thought I was going to pass out.
Kuala Lumpur; been only once but would love to return. If you get cheap enough flights it actually works out about the same price because the gate price is a lot less. Lovely well-designed for viewing circuit, gorgeous facilities, grandstand seats instead of suffering on the grass, and the best bit is the food. No scummy over-prices burgers, just the best satay, nasi goreng, rendang, cooked freshly and costing pennies.