So definitely know I'm late to the game with this response but I've been planning a trip and I took the opportunity to give it a little bit of a try.

I first called Visa Signature with a very specific question. If I'm visiting China on a Transit Without Visa is it possible for me to visit the Great Wall (there's a stipulation where you cannot leave the Beijing Administrative Area)?

I was completely underwhelmed by the concierges efforts as he just directed me to a website I could have easily googled

Visa Infinite concierge didn't quite grasp the question either and just found me day trips.

I did specifically ask the Visa Infinite concierge what the major difference was and he explained that other than a few more hotel options, there wasn't much of a difference.

That said, I'm still more impressed with the Visa Infinite experience than I have been with Signature in the years I've had the chance to use them. I've contacted them a couple times asking for some recommendations and both times I ended up talking to Alex D. The first time I asked for hotel recommendations and they delivered but not exactly what I was looking for.

Once my travel plans evolved a bit, I decided to give it another try and I was more specific with what I wanted: "I'm more of a shotgun approach kinda guy, Alex. Don't give me three hotels give me as many as you can based on what I described and I can do some legwork from there" and they definitely delivered. It took them some time but they looked up I think nine hotels in each of the cities I was visiting and I'm still working through it

There appeared to be a misunderstanding about one of the cities I visited and when I emailed them to correct it I had a response within a few hours.

TLDR: Visa Concierges do seem to have a few things going for them. My experience with Infinite is, in my limited experience, better but that may also have been me finally understanding that they're not mind readers and explaining what I want

Hope it helps.