ImAGeek wrote:Thanks guys, but I decided to just do Tomb Kings in the end

I'm a Tomb Kings player who recently switched over to Vampire Counts out of frustration with the army.
TK are good fun against casual opponents in a very friendly environment, but the more competitive your gaming group gets (which I've found seems to be a natural evolution for most groups the more they play) the more boring and frustrating the
TK become. They just don't have the tools to deal with all comers effectively.
That said, if you're looking to overlap then my suggest would be to play both armies skeleton-heavy. Wargames Factory has some pretty gorgeous
GW-alternative skeletons that are extremely cheap compared to the
VC variety ($20 for 30, rather than $30 for 10, and you get a discount if you buy lots). I'm currently running two units of 40 skeletons in my
TK-themed
VC list, with another unit of 14 as a bunker for my mages.
From there the overlap is actually more minimal than you'd think. I've toyed around with adding a "pillar of swirling sand" to my two caskets to function as mortis engines, which I think could be cool. However, for the rest of the models you're effectively just proxying. Halberdguard as
GW Grave Guard is an almost-acceptable stand-in, but most everything else your friends might get a little annoyed at you "never playing with 'real' models."
That said, overlapping 50-100 core skeletons between two armies isn't too bad. And if you paint them all up with a consistent them you'll have a pretty sweet looking force for your display tray. You can also recycle old models that have fallen out of favour for you into bits to convert options for your other army. For instance, my carrion and ushabti have long since been cut from my competitive
TK army. But hacking off the carrion wings to add to Ushabti and now I've got some pretty sweet
TK-themed vargheists. That's the real benefit to running the two armies in tandem, in my mind.
If you can find another
TK/
VC player to swap out bits with then you're really in the clear. I've got a few friends with "traditional"
VC armies, and I've gotten lots of bits throwing them the gothicy bits I don't want in return. I'm scratch-building "crypt horrors" out of the extra
CH arms and heads from my buddy's vargheist boxes, which I'm turning into "mummies." Should look awesome...when I get it all finished.