the safest pick would be Susan Rice, followed by Kamala Harris even if they don't excite us progressives.

I actually really like the prospect of Rice. She's obviously not a progressive dynamo, but she has an outstanding resume and we need her specific expertise to undo Trump's damage to diplomatic relations. She could do that work from the position of Secretary of State (and if she isn't VP she damn well better be SoS), but I also see her as someone who would rise to the occasion if she had to assume the presidency.

I have my fingers crossed for Warren for political reasons, but I have little hope that she will be picked. Of the remaining people on the theoretical short list, I like Rice the best.