Originally Posted by Willbur

This isn't true, you can combine points and certificate. I have done it on numerous bookings and have it for an upcoming one at Conrad BB in October. You have to call in to do it (obviously due to the certs) and you just have to find a rep that is knowledgeable. Those who are lazy or don't know will simply tell you that it can't be done, but just HUCA.

However, a certificate does not get you the full points value off, it gets you the prorated points off. The calculation works like below:

First, calculate the total number of points that would be needed for the 5 night stays with a 4th night free. So 150k x 4 nights = 600,000 HH points required.
Now divided that 600,000 by the 5 nights, so 120,000 average per night.
Each free night certificate used is going to save you 120,000 points, and not the potentially expected 150,000.
So using 2 free night certs, you end up with a stay costing 600k -120k -120k = 360k + 2 FNCs.

The above explains the mechanics, and the below is a quick shorthand way to determine the points needed when combining with FNC on a 5 night stay:
[Standard Rate] x 80% x [Number of nights you don't have a FNC to cover]
150k x 80% x 3 = 360k