Great feedback on the humidity -- that happened to me in Puerto Rico once. And that A/C hotel room situation is 100% going to happen again. What's a best practice there? Let the camera come up to temp before changing lenses? Is there any need for ziplocks and desiccant packs when bringing my gear back into the hotel room?
Hot air is capable of holding much more humidity than cold air. Relative humidity is a way of expressing how near the air is to its moisture holding limits. 100% RH is where you start getting moisture deposited on everything (dew point). However, seal that air in a bag and heat it up, while the water content is obviously identical, it'll drop below 100% RH. Dew point is a way of expressing at what temperature the humidity of the air will hit 100% RH - in the tropics, it could be 32'C, yet dew point could be as high as 29'C. Colder temperate climates preclude such high dew points, but the more dramatic change in temperature each day can result in dew point being reached as the temperature drops overnight.
A cold object in a hot humid environment is a no-no. Think of a cold beer straight from the fridge in the tropics - almost straight away you'll get moisture all over it. This is simply because the air on the surface of the bottle has cooled down below the dew point, and the moisture from the air covers it, often running down the bottle to form a puddle. A camera stored in a heavily air conditioned hotel room is much like a beer stored in the fridge. Big, heavy surfaces (metal and glass) which have a high thermal conductivity (unlike plastic), but due to their mass they retain temperature for some time. This spells disaster when taking your camera out of the fridge (hotel room). The best bet is to utilise the drier air of the hotel room to form protection while it warms up - put it in a sealed plastic bag before leaving and let the heat soak into it in the dry air. When it's up to temperature, take it out of the bag.
The other way around, whatever you do, don't use a bag. A hot object in cold dry air has no potential to invoke dew point, so leaving it out of a bag is perfect. However, cool down hot humid air, and like a cold winters morning in a temperate climate, it'll deposit its moisture over every surface it can reach. So, don't put the camera in a sealed bag when you walk into your cold hotel room!
My last trip to the tropics involved a long stay in a house without any aircon. No moisture issues with my gear at all, but there were rather severe heat build up issues with me