Two things on blood types:

1.  Do we learn Buffy's blood type?

2.  Does Spike ever order a specific blood type at a demon bar, or make a comment about what's best?

1. Nope.

2. Spike orders O-negative at the bar in "Goodbye, Iowa."

In Angel S5, Spike comments favorably that Angel is getting otter blood, which eww, must taste kind of fishy.  Angel gets otter blood as one of his perks for running Wolfram and Hart, so presumably it's expensive.

Angel got the idea that otter tastes good from Harmony, who got the idea from Spike (since she never had to bag it before working at Wolfram & Hart).

Sea otters are endangered animals, so it'd be illegal and noticeable for W&H to hunt them. They could be getting Asian river otters, but they're quite small.

The Northern River Otter, Lontra canadensis, is a North American member of the Mustelidae or weasel family. It is also known as the North American River Otter. It is a common animal in North American waterways. However, its numbers have significantly dropped since Europeans came to the Americas.

This playful, aquatic mammal is quite secretive and rarely seen by humans. River otters are typically 3-4 ft long and weigh 11-23 lbs. Adept swimmers, otters have dense, waterproof hair and webbed feet. Otters are nearsighted, which may improve underwater vision

(And for someone who used to eat rats, I'm thinking the size of the small mammals won't matter At any rate, it seems they just added a bit of otter blood to make the other blood better, cause Angel was all like "what is that" or something, and Harmony gleefully tells him how she adds otter to the mix)

"...it seems they just added a bit of otter blood to make the other blood better, cause Angel was all like "what is that" or something, and Harmony gleefully tells him how she adds otter to the mix."

Kind of like when I add a dash of nutmeg to spinach :nod:

Oh, yeah!  I just remembered that Harmony offers another vampire a light and fruity vole, or something to that effect.