Apart from this Forum, which gives exceptional advice, I talk to as many people as I can in hotels and often find out about new places this way. This is especially true when staying in an Amanresort, although these days Aman GMs are being quite guarded about letting out information as Aman do love their secrets. Having said that, I was just told that The Aman at Porto Heli has begun construction and the test room will be ready this summer, soooo....

Another good source is owners. If you ever meet one, ask them about their new plans and you will be sure to learn some fascinating secrets.