Answer to the riddle

Sorry about the delay on this... been having internet problems.

OK, here's the answer to my riddle.

For those of you who didn't know about my trip...

Clue phrases/words contained in the message:
"Maybe I'll go to an island or something."
"Beaches..."
"River..."
"Initially I thought about spending Christmas on Ishigaki" - this is a key clue!
"there are plenty of islands to the south of the Japanese mainland"
"maybe a cold one"... OK this is a red herring - unless the AC is cranked :)

What islands are south of the Japanese mainland? Okinawa, Ishigaki, Iriomote, Hateruma, Taiwan, Bali, Sulawesi, Australia...

Initially? Take the first letter of every sentence in the message, and it reads:

I AM GOING TO BRISBANE

There you have it!

GREETINGS FROM AUSTRALIA! I MADE IT!