Hi there
I can only speak for the Red Sea, as I havent ( yet ) been to the
other countries on your wish list.
Pls see also my comments on the Marsa Alam link on the net group.
I have dived the Northern and Southern Red Sea, and the latter is
definitely the best. It is relatively undived, by comparison, and
offers excitement on every dive. Think large shoals of hammerheads,
dolphins, white tip oceanics and large polagics. You simply don't even
bother looking at the reef sharks, cos there's soooooo many.
The only way to do the best dive sites is by a liveboard. I dived on
the MV Excel - pure 5* luxury, great cabins ( en suite and large side
by side bed ), the food was gourmet and the staff excellent. The trip
cost me less then $1500 for a week, which included a flight from the
UK ( where I was living at the time ) You want to be aiming to dive
"The Brothers, Daedelus, St Johns, Elphinestone and Rocky" These sites
are remote reefs that attract large profusions of polagics and can
only be reached by livaboards.
Contact Tony Backhursts tour operator www.scuba.uk - they do a land
only price where u can sort ur own airfare. I can't enthuse enough how
good the boat was.
The diving is awesome, the reefs pristine, the marine life abundant
and the memories unforgetable.
Go for it, u won't be disappointed.
Good luck
Submersible Sid

April is a good time for PNG (I went in March once on a live-aboard to
the Hermits and it was fine and was told April was good too!)