Looking a restaurant in LA, with amazing food and great ambiance
If you liked Ssam Bar and the tasty small plates dining in a more casual and lively atmosphere, I would recommend AOC. I just went back myself and rediscovered how much I enjoy it.
Urasawa, Providence, etc are more high end and formal.
While it's true that the physical space is not going to wow anyone the atmosphere is actually very nice because of one major factor: the service. And the lighting is low enough (without making you wish you had brought your mini maglite) to give it some atmospheric charm as well.
Ortolan is too romantic for a client dinner.
Can't rec to your references, but look up these trendy & delicious spots in that 'hood:
Bar Marmont 8171 Sunset Blvd
Or the Chateau Marmont at 8221 Sunset
Chaya Brasserie 8741 Alden Dr, BH
Comme Ca 8479 Melrose
The Foundry (live Jazz) 7465 Melrose
Grace 7360 Beverly Blvd
Although Ortolan can definitely be romantic, I have taken business acquaintances (co-workers and clients) who have an interest in great food there for dinner several times and they have all loved it. However, as it is a small kitchen, service can be leisurely so not ideal if the client is time-sensitive. I find Animal, AOC, and Comme Ca too crowded and noisy for clients (though I love the first two for casual dining with friends) but The Foundry, Grace, Lucques (where OP has already been) and Providence are all good suggestions for the West Hollywood area. While I like Bazaar, it is a tough reservation at the moment and it would depend on the client's tastes whether it would work.