I tried a JL shopper last year for a dress for dd's summer wedding. She was very helpful, but there was literally NOTHING suitable. I did not want typical 'mother of the bride' stuff, especially not in ghastly salmon pink! More than one helper in more than one shop seemed to think this was perfect for MOTB.
Nor did I want anything too short or sleeveless or very fitted. I wanted something pretty and comfortable, not too formal, but stylish. It was hopeless. Anything where the fabric was really pretty was invariably the wrong sort of style - I.e. might well well looked nice enough if I were 46 and still a size 10, instead of 66 and a 12/14.
In the end, and almost in despair at finding nothing in what is considered a very good shopping centre, I found a really lovely blue and white linen dress online, at Poetry. I ordered 2 sizes since unsure, they arrived within 36 hours and I was able to return the wrong (larger!) one for free.