The weird thing is that you are trying to second guess how a name will be percieved in 16/21/30/40 years time.
Fashions change, perceptions about names change. We know that names we used to associate with elderly people but those elderly people were once babies and these names are now being given to babies again. By the time those children are applying for jobs, those names won't be associated with elderly people anymore, at least not by their peers.
I think the same applies to 'common' names or unusual names. All it takes is for some perfectly conventionally named person to become a popular glamour model, footballer, singer or reality tv star and it'll become popular, and common as muck. If you named your baby that name the year before it became popular, you'll still find them associated with it as they grow up.
Okay, there is a good chance that a John, David or James won't date too much as they are perpetually common (so aren't associated with any particular name-bearer or era). But life would be pretty dull if every child's name came from the top-20 names of all time.
One name that I love for a boy is very unusual. Easy to spell and pronouce but some people might think it is a bit weird. My DH has even come around to it, though not for this first child (there is a family name he is determined to have which is extremely conventional - just like his own name [sigh emoticon] ). My biggest argument in favour of showing my choice is not unusual? There were more babies named that last year, than were named my name. There were only a few babies registered with my name. But in my primary class at school there were 3 of us. My name isn't weird, or horrid, or hard to pronouce, spell or remember. It just seems to have fallen out of fashion.
I might be tempted to do a Lorelai Gilmore and name a future daughter after myself just to save the name! Hey, if men can do it!
Basically, I think that you should choose names that you love. Its surely better than trying to predict:
a. where name fashions will be in 20 or 40 years time
b. which name has negative associations for an interviewer because they were bullied at school or have just had an acrimonious divorce
c. what name will be considered common/posh by the time your child writes up a cv
d. what the name of the really distruptive pupil was in the year above your child
e. what name will become associated with a celebrity
f. what name will become associated with an unpopular politician
g. what name will become associated with a victim of a horrific crime
h. or the perpetrator of the same
i. what career your child may choose (hint: it may not be the one you envision for them, it may not even exist yet - just think of all those creative technology jobs that didn't exist 30 years ago).
So you can pick a name so common and perpetual that its unlikely to become connected with one news story, era or class. Which is fine if you love it. Or you can pick something else you love, cross your fingers and hope your child loves it too. If they hate it, perhaps for reasons you can't predict now, if they feel it limits them in their choosen career whether thats to become an accountant, a doctor, an artist, a plumber etc. Then they can change it.
I'm not saying that people won't react to some names and that may affect your child's perception of themselves. Especially if they are someone influencial in your child's life like a teacher, family member or sports coach. It might happen and you might need to counteract it with plenty of contridicting that expectation if you think your child is hearing limiting things - by praising Daisy's athleticism and intelligence rather than focusing on how pretty or well behaved she is. But people judge others on all sorts of things, its not necessarily right or predictable.
A popular Tabitha will find that others think her name is cool and unusual in a great way. One who struggles socially may find that her name is picked on, but that's not the reason that she is bullied. Being called (Contrary) Mary, (Lazy) Susan or (Plain) Jane wouldn't have prevented it.
There are few situations where we are judged soley on our names - possibly job applications if there isn't an equalities protocol which prevents/monitors this (sometimes personal data is kept seperate from the main CV to reduce predjudice based on sex, ethnicity etc). But how do you know what career path your child will want to follow and what names will be in vogue in that industry in 20-30 years time?