My next visit...

You could try Amazon. Here in Thailand they are available in the camping sections of most big stores - to be honest I never found any I got on with, so gave up using them a few years or so ago. Now I to entertain myself seeing if I can flick them into the distance - they always come back though ;+)

FYI for your 3 locations this year you shouldn't need them in mid November onwards. If you do buy some avoid the "shiny nylon" ones - they slip down inside your boot/shoe if the sock section is nylon. Nylon uppers are OK. Just plain cotton are probably the most common and cost effective.

Thanks for sharing your pics!
Kaeng Krachan is not an easy park. As you have probably noticed, Khao Yai national park is generally more productive.
The great draw of Kaeng Krachan is the lower visitor numbers (even though weekends these days get crowded; but at least whenever you hit a trail on foot, you are unlikely to meet any humans.) and the park has a more impressive species list than Khao Yai, but most are species you almost certainly are not going to see on a relatively short visit of a couple days. However, it is the species list what keeps it exciting especially for naturalists living in Thailand, because returning often will sooner or later hopefully reveal those rarities.
For most people interested in wildlife watching coming from overseas for holiday, I would recommend Khao Yai over Kaeng Krachan. The consistent success I have had in Khao Yai, I have not experienced in any other park in Thailand. At least if you like to see a variety of mammals, birds and herpetofauna.

I think a few reasons for this are better accessibility in Khao Yai (better trail and road network).
Another reason is the higher visitor numbers. That might be the opposite from what you expect, but you can see the same effect worldwide in the most famous popular parks. Go to the big African parks and the lions and whatever other animals just sit down next to your car. Some people think this is unnatural, but actually it is not. It is for the same reason why a deer not runs off when it sees an elephant. They know the elephant is not going to do them any harm, so there is no need to worry. Tourists are not hunting them, so the animals become relaxed over time and will just continue doing what they would be doing if you were not around. So showing their real natural behavior.
In Khao Yai, both the road and trail networks allow visitors to have better access to a much larger area and that together with the continuous higher visitor numbers means more animals get exposed to people on a daily basis and therefore get the chance to learn that these people are not harming them.
Therefore e.g. lots of the gibbon families in Khao Yai will allow you to get relatively close. In Kaeng Krachan there are only a couple gibbon families near the roads that are more habituated to humans, but many of the families even those having territories close to the road are very shy and most of the time you see not more than a glimpse, or jut moving branches.

The Dusky langurs are mostly calm near the roads. But as soon as you get on the trails where very few people venture they are extremely shy, and you will hear them rushing away in the tree tops even when you are still 100-200m+ away.

It is nice to be away from the people, but it comes at a cost ;-)
For primates Kaeng Krachan is quite nice, with a bit of effort especially if you have a couple days it should be possible to see 4 - 5 primate species. But often enough, in terms of bigger mammals, there is not a lot more you will see. But for birdlife and herpetofauna, Kaeng Krachan is pretty good.
Kaeng Krachan definitely has potential, and if night drives were allowed, it would definitely significantly increase the number of mammals. But as of now, that is not allowed.
Or otherwise you just need a bit more luck ;-)

Don't worry, I did not take your comments as a complaint ;-) . You added that you enjoyed your trip. It was more general information for any other visitors who read the post and plan to come to Thailand for the first time and wish to see some wildlife. Often they think that in the more quiet parks they will have a better chance, but that is usually not the case. Still as an overall experience it might be more pleasant in a quiet park and if you take it for granted that you might not see as much it is beautiful to visit all these places.

Seems like you did get lucky with the Yellow-Throated Marten sighting!
Cool! And the Ferruginous Partridge!

The pond heron shot is really nice. Is that from the little hide Ian put up at the little lake on their property?

I have never visited those bird hides. But have seen some pics, with obvious human-made setups. Concrete rims, branches clearly cut off by people etc etc, haha. Not to mention the food piles.
Though I guess a bit of distance is wise, also because (not sure at which one) I have seen pictures of bears visiting too, ;-)

Another great haul of pictures Zuppi!