I have only played with the Curse of the Dark Pharoah expansion for 3 games and then Black Goat in the Woods for 3 games, 2 with the Herald. My wife and I started playing with 2 investigators each also. All this added a lot to the game, increased tension, and increased playing time because of so much more to take care of each turn playing 2 investigators each. However, I think we will always play 2 investigator from now on.
Curse of the Dark Pharoah really made the Terror Track go up fast for us, something we were not used to with base game. Black Goat made the Ancient One awaken faster because of Double Doom Mythos even without the Herald and with it the Doom Track went up even faster. The last game with the Black Goat we didn't think we would get 6 gates closed, only had 2 because of clues tokens being scarce, and was awaiting the AO but then kind a lull happened with the Mythos and we sent in 3 investigators at once and closed 3 gates without any delay. Then luckily closed the last one a few turns later. I can't say the Black Goat expansion with the Curruption Cards hurt us much. In fact in 3 games we have not even drawn one or taken a membership. The Location cards however don't let you get the items the location icons say you might get, like clues, commom items etc. Then the OW cards you get delayed quite a bit. This is what made the game more difficult for us with that expansion, plus more monsters with the Herald. Again Curse of the Dark Pharoah the Terror track went up quickly.
I have used dice to keep track of how many monsters are allowed in the outer limits. I just put a die on there with 4 to remind me, another one next to it with 7 for the amount of monsters I am allowed on the board. I also used dice on the first player marker and turn it 1, 2, 3, or 4 for whoever goes first each turn. Seems for me that was easier than passing the first player marker around and forgetting to do it a lot of the time. I put a die on the AO to remind me how may gates open it takes to awaken him. Also during final combat, we usually count up what we can use and keep track of that number with a die for combat as well as the Skill check the AO uses when it attacks where it goes from plus 1 to 1 less each turn. It so easy to lose track when you are fighting so I just slow down, change the dice etc and then go for it.
I was fortunate enough to have some extra cash and bought all the expansions online at a good price. I read the rules, cards and get acquainted with them so when I do play with them I am not looking up rules or having too many questions about how cards work. (although once I start playing there is still a lot of head scratching).
Anyway I am going to start TIBS league now that I have all expansions just to learn the ropes better. I cannot see my enthusiasm dimishing any for this game. I bought a nice green felt to put on the table when I play. I ordered some 20's music from Amazon along with some Horror music CDs from Amazon and the mood is pretty good. It is sometimes amazing how the music will fit the mood of the game.