I recognize that Spain is a late night place --if making a reservation, how late should we make our dinner reservations?

They usually don't eat until around 10pm.

If you don't have time to make a reservation, just walk in anytime before 10 and you'll be the only ones there!

I agree absolutely with the above...probably no earlier than 10 PM...a lot of the restaurants don't even OPEN until after 9PM so "how late" might not be as much of an issue as "how early." And, depending on where you want to eat you may not even need a reservation but I would ask at your hotel...there are SO many places to choose from, at least in the larger cities, I doubt you'll have much trouble. Enjoy it!

Some cities in Spain are notorious for being unsafe in term of law and order. If we have dinner so late, is it safe to walk around the city, such as in Barcelona, to search for a good restaurant. I have heard too many stories about mugging, things being stolen, etc,. My first thought is to have dinner in the hotel where we are staying, but obviously it's not the way to experience some good food.
Any suggestions?