Lost city in the Desert of Skulls, proper walled-town Arabian Nights style. Why abandoned? Not covered in book, perhaps a water source dried up or a caravan route changed.
Large scale underground, essentially as soon as you pass the gate you go straight down a flight of stairs and don't emerge again for anything other than a deathtrap. There is a route that exits through a one way door outside the city walls (a GAME OVER), so presumably lots of secret ways of ingress scattered around the desert. The ruler of Vatos is the priestess Leesha...
Buxom evil enchantress. Laughter causes paralysis (one of the GAME OVERs of the book). The only weapon that can harm her is the tooth of a Giant Sandworm (or perhaps that of a Purple Worm in a more vanilla, less world-specific D&D). You'll have to dream up exactly why both of these things work yourself.
Has a cadre of guards one is blind, another deaf-mute and probably eunuchs- typical fat, bald, bare-chested harem guard types with pyjama bottoms and scimitars. Sponsors an art competition, artists are granted Ring of Protections that leave them immune to harm, winner receives large prize, losers executed. That sounds an odd conceit but if you're the evil overlord why not surround yourself with nice things? There must be plenty of egotistic artists and poets who cannot comprehend not winning.
Remarkably underemployed by Livingstone, once confronted with the tooth does a runner and to the best of my knowledge never shows her face in an FF book again.
The real BBEG, basically just lodging at Vatos presumably with Leesha's favour. Interesting idea as it seems apparent that Vatos is not Malbordus's dungeon which is quite novel and a bit of an inversion of the usual arrangement.
Drop out living in rooms full of scavenged tat. Has a staff which turns into a deadly venomous snake when tapped on floor. Good example of a neutral character who may be an ally to the party who lives safely in a hostile dungeon by nature of his protective staff and presumably from being beneath contempt/notice.
Sword Arm Corridor
Four statue arms clutching swords sprouting out from corridor walls.
Messenger of Death
Spectral adversary, effectively shouts "Boo!" at the player and runs off. Leaves the letters D, E, A, T & H in five separate places ahead of the player, accidental discovery of each causes SKILL, STAMINA and/or LUCK loss, if all five are found, Messenger of Death materializes to watch the player expire (A proper No Saving Throw job).
A corridor strewn with broken glass. Mysterious figure throws a glass bottle at party which breaks revealing a scroll in an unknown language. Read Magic or similar reveals it to be a Mummy's Curse with serious deleterious effects. A nice piece of gamebook design here in that the option to cast the Read Symbols spell tempts the player into triggering the trap whilst the broken glass should act as a hint not to.
Skeleton Warriors with Sphinx Headdresses
Just really cool.
Giant Fireflies With Random Electrical Attacks
Bronze Idol Statue
A bronze statue of a youth with two-handed warhammer. If the shadow is crossed, animates as Living Statue, Iron and attacks. If passed on the other side remains inert. (A neat Fire on the Water style visual puzzle - a dying man tells you to beware of a shadow and the illustration shows a shadow and then asks upon which side you wish to pass).
Pass a test of general manliness to gain a boon, fail it to be punished.
Mutant humanoid fighting with a rod akin to the Well of Lost Souls key in Raiders of the Lost Ark. A sort of solar/laser attack from the gem in the rod. When dead, ceiling starts lowering just for good measure.
Ferric-munching ceiling denizen. Harmless to flesh but destroys helmets. Presumably rolls one attack, if hit dissolves helmet (if worn), AC-1. Can do little else but sneak back to ceiling very slowly. An irritation to remind the players to look upwards even when there aren't obvious
A Golden Chalice that summons a Wind Elemental to fight for the wielder with the immortal magic words "Barrabang Hinpo Garrabang". (Probably means something important in dodgy Bangkok nightclubs...)
There's no real "best path" through ToT that minimizes the risk to the player - you will still need to pass at least one Test Your Skill and one Test Your Luck to survive, a Test Your Luck is required to acquire an item without which the battle with the Night Horror will seriously drain your SKILL and there is an unavoidable SKILL 10 STAMINA 20 monster before you get to Vatos. Accordingly I have no desire to return to the gamebook and "do it correctly" with the dice and no cheating.
(Temple of Terror illos by Bill Houston, copypasta'd from a really poor PDF scan hence shitty quality of reproduction)