I am constantly trying to determine new places that have that atmosphere that makes you want to keep ordering 1 more drink just to keep your spot.
Top Tier Places for me have been:
MASA (Bar Area)
Where else do you all go for a dinner night out with a little bit more of a vibe?
I agree with you on ESK and Cuchi Cuchi. I haven't been to the others yet. I'd add Scampo, Gaslight and River Gods. I personally find Scampo to have too much of a vibe, and not one that I goove to, but it's pretty lively. River Gods is more casual than the places on your list, and it's not a culinary destination, but for a limited menu and better-than-I-expected cocktails, it's a fun place to hang. Gaslight hits the sweet spot for me in this category, and if you tire of sitting at your table, you can move to the sizable bar.
The Hawthorne in Kenmore Square not only has amazing cocktails (see other posts that go into more detail) but also a fun room with the most comfortable chairs I've ever sat on. I like how there's plenty of space so you don't feel like you're sardines in a tin, and the noise level was lively but low enough that I could talk without shouting (at least on a weeknight; I'm not sure how much of a zoo it is on weekends). There's also a separate "living room," which our server gave us a tour of. She said you can request sitting there whenever you come in or when you make a reservation. You can bring your iPod and slap it in the dock hidden behind one of the pieces of artwork in the room. Depending on how many people you're with, it could be like your own private party!