I like blue and gold roses, pink and white anything, orange and black (tulips), orange and blue pansies... I actually prefer displaying hybrids with non-hybrids.
I have a lot of pinks/blues with yellows and whites, purples with whites (and sometimes yellow), oranges with yellows and reds, etc etc.
I love any combo of carnations. I also think purple and white roses look good together. Blue and black roses. Purple and black tulips. Orange and black roses. Purple and gold roses. Pink and white tulips. Yellow and pink lilies. Those are just some of the combos in my town. I tend to match flower species together and just vary the colors. I just don't think putting two different flower species together looks right for my design purposes.
Blue violets + pink cosmos, pink tulips + pink cosmos, white carnations + blue roses, but my favorites are blue pansies + purple pansies. Good luck redecorating your town!
I have black and red roses by my pwp tower, pink and white carnation in front of my town hall, blue and purple roses by my Egyptian areas, and purple and red rose by the totem poles. I really like those places cuz of the flower combinations.