The hotel in Singapore from which Dr. Elizabeth Fielding (Pat Crowley) emerged only to be spirited off to Wo Fat's hideaway somewhere in the Pacific was, in actual fact, the Halekulani Hotel in Honolulu. The hotel became popular in the 1940s and 1950s and could have and should have been placed on the National Register of Historic Places for its Pacific Rim architectural details, alone.
But, no. First, the beachside bungalows were taken down and a high rise built in their place. Now, the main building, which we saw in "Termination with Extreme Prejudice" (Season 8) and "Woe to Wo Fat" (Season 12) has been replaced by uber-modern structures that stand apart not at all from so many others in Waikiki. Such a shame.
If we study pictures of vintage hotels in Singapore, we see definite similarities in architectural styles to the Halekulani. Here are links to two:
* Raffles Hotel. Although it is much grander than the Halekulani, if we study the main level, we see how it might easily have influenced Hawaii Five-0's location manager when deciding where to film. The Raffles is an uber-expensive hotel with rates in excess of $1,000 per night! This is probably not where real-life research professors would stay while in Singapore.
* Village Hotel Albert Court. Again, we see a similar style with a courtyard for guest arrivals and departures. No prices are given for rooms here, but the photographs indicate they are probably high. https://www.tripadvisor.co.za/LocationPhotoDirectLink-g294265-d306155-i86462508-Village_Hotel_Albert_Court_by_Far_East_Hospitality-Singapore.html