Choosing a decor for your restaurant can be a very fun process. You get to decide how the restaurant looks and how it feels for the guests and for the staff. You might want to get some professional help from a designer, someone who really understands the elements of design, the uses of color. The way things are placed in a restaurant can have a profound impact both on how it feels to be a guest and how it works for the staff when they're trying to do their job.
Obviously, an architect is a great person to talk to about interior work and design and use of space. It's also important to involve someone who can do some thinking with you about how to express your concept and your idea in materials and colors and placement. Will you have flowers? Will there be art? Will there be music? What kind of flowers? What kind of art? What kind of music? Any one of those elements can be adjusted slightly and change the feeling of your restaurant.
So enjoy thinking about design, but don't make it what your restaurant is all about. I'm pretty sure you've been to restaurants, and I know I have, where all that's there is a lot of design. Food's not so great. Service isn't there, no hospitality. It's all about the way it looks. It should be part of what you offer your guests. It should be something that fits in with the whole. Your concept, the space, the food, the design, the beverage offerings, the staff. It all is part of a whole.