Bridesmaids step-halting down the aisle in matchy-matchy dresses are almost as passe as those identically dressed women on Lawrence Welk ( read: almost. Lawrence is in rerun mode lately and brides are still ordering cookie cutter gems in quadruplicate). Giving your ladies a color or monochromatic scheme to work with has proven a great way to keep everyone cohesive yet individual. And happy. Do you realize how many pissed off bridesmaids I've seen in my twenty-odd years of dressing brides? Not everyone looks good in dropped waists. Or mini skirts. Or portrait collars. Think about this simple premise: if she looks like herself she's more likely to relax and feel good. Giving your party more leeway also lets each express herself with her own personal touch. Face it, no stylist or fashion artist can really put your friend's trademark on like she can. And every woman has some personal thing about her that makes her unique like wearing barrettes in her hair; showing off long legs or going a little Goth.
Lee Klabin
My best advise on this is to give everyone clear guidelines about color and the type silhouette you want. After that chill out and realize you can probably trust your friend's judgement. Those shoes she likes so much that make her unique probably will look great in satin.

Above is an actual case in point. A real wedding. Katie's bridesmaids chose their own styles of tangerine or strawberry-colored dresses. Her sister, the maid of honor, wore an ivory bolero to stand out.

Another way to keep everyone linked is to purchase a fabric you love in bulk (enough for all your maids). Have them all go to the same designer or tailor to have a dress made up. Though you'll have different styles, maybe some with cap sleeves and others sleeveless, it's okay because the fabric will be the factor joining everyone together.
Don't want to bother with tailors and fitting appointments? Well, if you can believe it, the quartet above are all wearing the same dress. I didn't believe it until I studied out the Two Bird website. The designer offers 11 colors and each dress in the collection can be worn ten different ways. Wowzer! This is one of the best solutions to the bridesmaid dress dilemma I've seen yet. Kinda like the best thing since sliced bread.