We ran a bunch of Klingons and Romulans in an old Spelljammer campaign. Used the base stats of orcs for the Klingons and Elves for the Vulcans but we made them stronger. Go with what feel right for your campaign. I tend to run Klingons as Vikings and during the Spelljammer campaign they were the raiders most feared by the party.
I like the idea of using a dwarf style template for Klingons. Yes the Klingons are big and all that .. but I think they are an honor bound warrior society more resembling a Dwarven code over the crazy chaos of orcs or hobgoblins.
Using the elf template for Romulans or Vulcans is tempting due to the physical similarities but culturally speaking Roms and Vuls have nothing in common with elves. (At least most 'average' elves.) I see elves as free spirited and emotional. Romulans might be a little 'drow' based. The average Vulcan would have more in common with a human NPC monk than a wood elf.
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Just trying to help out.
Using the elf template for Romulans or Vulcans is tempting due to the physical similarities but culturally speaking Roms and Vuls have nothing in common with elves. (At least most 'average' elves.) I see elves as free spirited and emotional. Romulans might be a little 'drow' based. The average Vulcan would have more in common with a human NPC monk than a wood elf.