is the trim fabric strips applied as banding or actual trim, like fringe?

Fringe will be bulky esp. at the points. Mitering it and trimming the bulk would help reduce the bulk but sewing it would be a chore, esp. 14 of them. If it's banding, that wouldn't be nearly as bulky but again application is time consuming esp for 14 of them.

The runners look nice, she must want to match her color scheme. Maybe she'd consider a banded one for the head table and rosettes on the rest? Or tassels on the points?

Brides can be picky, it is their day after all & they like to be the star & have it all their way, for that day only (hopefully)...

I would say the rose pedals and a red tassel on the end would be really pretty..

Or if you can find wooly nylon thread in the right shade of red,and you have a serger you could serge around all the edges,it would be quick and easy.
Kathi

I frequently use grosgrain ribbon on place mats and runners and have no trouble folding them to go around the corners easily. You might try this. You can get the ribbon at any fabric store or a store like Michaels.

I think part of the problem is that your table runners are already hemmed. Adding anything substantial to the edge makes it too bulky. You might consider something like rick rack sewn along the edge to minimize the bulk.

Thanks everyone. The wedding has already come and gone. The table runner in the picture above was given to me with the edges already turned under. Pris, I thought the same thing, so I tried doing one without turning the edges under, and just cut the points on each end. Once I told my daughter-in-law that it was going to take alot of red fabric/trim to go around 14 runners, she decided against using any kind of red trim at all. I went ahead and finished all the others just like the one in this picture. She just put some red docorations on each one.