Welcome back
The new store is gorgeous. The staff is friendly and inviting especially compared to the old store (the concierge will pair you with someone available, and or you can just walk in and browse). There is more stock; more places to sit; more refreshments

Once you find an SA you like, I prefer texting for appts, bc it can be busy. If you can, go during the week.
DH tells me that the mens dressing rooms are much nicer, but our SA said that was bc he was in the MtM room.
Re reservations, other people will know better, but it’s best, Post Covid to reserve in advance.

I still think it’s very hard to get decent Mexican or Peruvian Sushi in NY. And, I’m a bit tired of tasting menus and omakase. Prices are comparable to London, or a bit less.
ETA: for custom shirts for men or women, I find that Turnbull & Asser is much happier to experiment and try new things in NYC than in London. IMO, Bergdorfs is a bit tired, and Saks is having a bit of a resurgence, but I personally prefer boutique shopping along 57. Madison still has a significant amount of boarded up storefronts.