Like others have mentioned, in addition to the color of the bridesmaids' dresses, I think you should also consider the time of year/season, the time of day, & formality/venue of the wedding.
DH & I got married at 3:00 pm on a Saturday in April - the flowers in mine & the bridesmaids' bouquets & the table centerpieces were very springy. We had a traditional church wedding.
My bridesmaids' dresses were French blue, but there were some pink & yellow accents brought in mostly w/ the flowers.
My mom's dress was a light pink chiffon dress. My MIL's dress was a dark pink brocade & beaded suit.
In contrast, DH's younger brother & his wife got married in late November in his college's chapel w/ the reception following at a separate venue - a southern mansion used for various events. The wedding began in late afternoon, & the reception carried into the evening. The bridesmaids' dresses were navy blue. DH's mother wore a dressy gray suit, & the bride's mother wore a deep plum dress.
DH's niece got married in July. She had an outdoor wedding on a farm that started about 4 or 5, if I remember correctly. The ceremony was outside, & the reception was inside the barn. The bridesmaids' dresses were champagne-colored. My sister-in-law (the MOB) wore a Kelly green dress - it looked very fresh & summery & young & went great w/ her coloring! On the other hand, the MOG, who was only about 3 years older than the MOB wore a brownish-gray dress that looked very dowdy & heavy - and didn't fit the venue & time of year at all.
If the bridesmaids' dresses are black or black/silver, what color are the flowers in the bouquets?
W/ black bridesmaids' dresses, you can go w/ a lot of different colors for your MOB dress, but you don't want to clash w/ the flowers. Depending on the other colors (if there are any) being used for the wedding, a platinum, turquoise, cranberry, plum or grape, or even a berry pink or a coral could work well - I'd look for what works well w/ your coloring & overall style!
Regarding dictating what my quests should wear... I can't imagine! I mean, I can understand if the bride & groom have a "theme" & request that their guests dress to go along w/ their theme (like a Renaissance Faire wedding for example) or state something like "black tie" on the invitation, but, beyond that, it's really rather rude to ask your guests dress only in black so that you can be the center of attention.