with a white or light blue shirt, you could literally pick just about any tie as long as it's not black.
With a lavender or pink shirt, you could also have a good selection, but something closer to either the pink or lavender would work best. I.E. Lavender shirt, dark purple tie, with a navy suit, good looking brogue and a contrasting pocket square, perhaps a light blue paisley or polka dot, would be excellent and would be my choice in a fall or winter situation Match the socks to the square, the tie, or the shirt for some fun or to your navy suit to rain it in. You could also go white cotton pocket square to bring it down some as well.
If it's in the fall or winter, I would suggest a wool or cashmere tie to set yourself apart from the crowd... and in so doing get the bridesmaids' attention as well.
If in the spring/summer, a bowtie might show well, or a cotton tie with a small pattern and light summer color, perhaps a lime green or baby blue. Personally here I would go with the light blue shirt, with a cotton paisley tie in a light color in the spring, and pick up one of the colors in the paisley with the pocket square.
Hope this helps!!!