I abbreviate only when referencing multiple properties in posts on FT, or in other informal written communication. In such cases I always use an apostrophe to replace the Aman prefix. I think this is acceptable because it would be cumbersome to write out the full names of many properties in a list, and I view this as no different form other common abbreviations such as FS for Four Seasons, etc.

'The Amanpulo' is simply incorrect, as the is not part of its name. In some cases however, I find it acceptable to use the before the name of an hotel. If referring generally to a Four Seasons hotel, I will say 'I stayed at the Four Seasons' (omitting the location). Another case when I will use the is when a name does include the in a foreign language. For example, I might refer to Le Meurice as 'The Meurice' when speaking English.

Particularly on an internet forum, abbreviation is perfectly acceptable if not used excessively or in an awkward manner. Critiquing another poster's writing style is in poor taste, and that I dislike.