Cool place for a pre-opera bite/drink (walking distance to Civic Center)?
The Grant Grill bar is an excellent choice.
Currant is also nice for pre opera dining and usually validates parking.
Dobson's is also an option.
The opera's website also has a list of places to eat under the "Your Experience" header broken down by walking distance.
Have fun at Renee Fleming - actually listening to the rehearsal right now.