AA/BA top tiers do give premium lounge access. If you fly transcon premium, BA GGL is not much harder to maintain once obtained under the current requirements and earn structure.

My limited observations in the past year post upgrade bidding have been that AA upgrades remain for own CK/EXP, incl. transcon where the F/J demand for some SFO/LAX flights is still lower than pre-COVID. YMMV.

Notwithstanding the above, my decision has been to keep CX status in the US, as I still fly sufficient CX and Asia, and haven't needed the US upgrades. For NY lounges, personally quite like Soho and find it not much inferior to Chelsea outside of F&B.