AMC changes their pricing based on where you live. It's $24/month in California
If you pick the most expensive tier, then you don't pay any extra fees for tickets at that tier of theaters or any lower-tier theaters. If you get all your tickets at the theater itself, you pay no fees at all beyond the monthly subscription. (However, 4dx, 3D, and "PLF"/Imax showings are always treated as "higher" tier than your current plan, even on the highest-tier plan, and always incur an extra fee. Per Deadspin, Regal is still trying to decide whether to offer those as part of an unlimited monthly plan.)
If you have a Regal membership, you still get points for purchases at 100:$1, including your monthly subscription payment.