I think it'll be easier to meet up at Sol, cause the venue is a little bit 'hidden'

6:30 pm is a perfect time for me.
There are a ton of good restaurants at the zone. It depends on what are you looking for. Spanish, italian, mexican, indian food??? LOL Tell me what you want and I'll search something nice for you.
Tell what zone you would like, cause here what we call 'the city center' is incredibly big, but I suggest something around Sol/Plaza Mayor/Opera , Gran Via/ Fuencarral/ Bilbao or Chueca - mmmm I went there a few days ago and there are a lot of really nice restaurants...