Albino radscorpion or something smilar Swampfolks.

Well I went digging in the Vault to go look for some cool creature and here's what I found ( That would fit)

Mutant Cannibals (If the great divide is in fact the Grand Canyon)
Endless walkers ( seem like a really cool enemy, one of those once in a blue moon encounter ones)
Toads/ Frogs ( is there really some reason we don't have any of these? Did they go extinct?)
Spiders ( Yeah i know, some people have aracnaphobia, maybe implement an option to take them out?)

And uhm...yeah. About it for now.

Floaters ( They were originally supposed to be in the game so I don't see why not)
Catfish Mirelurks ( again, why not?)

We'll just say the Aliens helped the Chinese thus we just kill them all sense that makes them COMMUNIST.

http://fallout.wikia.com/wiki/Mutant_cannibal

It would be nice to see some V.B. concepts implemented. I know, Honest Hearts will not contain Burham Springs but I think the Gehennae / Molechs are real interesting creatures. Floater's finally brought to 3D is also an option. Aaand not to forget the lovely Pigrats.

a mecha spider would be nice especially in old world blues

Because they're cliche.

Some more humanoid enemies that have some more firepower would be nice.

Excellent choice.

Also, Swampfolks, Albino Scorpions
Queen Albino Scorpion
Mirelurks
Horned Kangaroos
Wanamingo
Maybe 1 or 2 Talking Deathclaws (Would be a very nice Easter Egg)
Gehenna
Molech
Giant Wasps
Maybe some kind of Boss Ghoul, harder to kill than a Reaver.

This is going to seem like an odd 'enemy' to add. Possibley more of a hazard than an enemy out to get you but, I thinksome sort of mutated/irradiated cactus dotted around the map?
No they don't walk after you but, if you get into a fight with an enemy and start your circling fire routine and don't pay attention to your surrounding and accidently walk into one you become poisoned real bad and can on'y move at 'overencumbered' pace.
You can destroy them but, they can grow back within days.

Or Giant Funnel Spiders that you have to really train your eye to see their hiding places?

Exactly. Not to mention they were in the nightmare of....Mothership zeta