I'm surprised you like the KGX lounge, nothing special whatsoever. Well I've always found the staff very friendly (opposite to your review) but the lounge is dull, grey and has nothing much going for it.
There used to be some plants there to cheer the place up, but NXEC got rid of them pretty quickly and EC never brought them back. There were originally going to be more sofas (according to the pic from the EC website:
http://www.eastcoast.co.uk/about-us/Latest-News1/Improving-your-First-Class-experience/) but they never happened.
The best part about the lounge was you could buy food and drinks (alcohol and non-alcohol) from the buffet menu, but that's now been removed too. There's no pub in KGX so being able to have a beer in the lounge on a Friday evening made a lot of sense.
They have added coke to the complimentary items now, that's the only thing you can call an enhancement.
The other lounges have dived in quality. Leeds has needed a refurbishment even in GNER times. Edinburgh used to be quite nice in GNER times (good fishtank, excellent staff) but it's now self service. Newcastle is now unstaffed.
These lounges are very disappointing compared to what the airlines offer. Have you ever visited a BA galleries lounge or the recently refurbished bmi domestic lounge in Heathrow? Just like on-board though, I don't care if I have to pay for food and drink in the lounges (you don't with the airlines though) I just want them to be available.
Best rail domestic lounge so far I've been to is Paddington, it had a lot more character than the dull EUS and KGX offerings although didn't appear to have the option to purchase food and beer. I did like the old KGX lounge though, had a lot more character. Let's see what they do with the new one, although I've lost all faith in East Coast delivering a premium experience.