Victoria & Albert's x3 (including once in the QVR)
...and once more this coming Feb' (at the Chef's Table, can't wait!)
It sounds stupid, but V&A is an exceptional value for this level of dining. Amazing food, unrivaled service, and no kids.

California Grill x3
We sat in the wine room twice, slightly less noisy, more cozy. This most recent time was probably the best.

Bistro de Paris x3
Love that tasting menu. Get a window seat for a wonderful view, esp. during Illuminations.

Le Cellier x3
Much happier with it since dinner has been upgraded to a Signature menu. Very enjoyable.

Crystal Palace x4
...always for breakfast. My favorite breakfast buffet, and the characters are fun.