Ethics of Tipping at High End Restaurants

What do you all think about tipping at high end restaurants? I mean places that charge $120 + per plate excluding alcohol.

Reason I ask is that I went out to an iron chef's signature restaurant Vegas for my mom's birthday, and the bill came out to $800 for 5 people pre-tip. Am I crazy for thinking it's totally fine to tip 15% on that instead of the usual 18-20%?

That server is going to take home $500+, probably closer to 1k, in tips for that evening. I've been a server for years too, and even then 15% seems more than fair.