I have a VERY common name for women my age-ish. To the point that at one doc's office, there are 14 of us with the same first AND last name. 14!!! There are two at my hair dresser's (and apparently, we're on the same hair cutting cycle). My given name is Jennifer. I go by Jenni. Until 4th grade it was 'Jenny' but I wanted to be different, so my mom suggested 'Jenni' which is quite logical - just drop the 'fer'. I liked it, we changed it, and my teacher told me I spelled my name wrong.
Jenni is fine, but I don't love it. It seems to be a bit childish with the "ee" sound at the end. In 5th grade (when I moved to Germany) I tried to start going by Jennifer, but kept forgetting and introducing myself as Jenni. Now that I'm starting a new job, I thought about going by 'Jen', but alas, I found this job through a friend who introduced me as 'Jenni'. It's hard to get past that first introduction and I hate constantly correcting people, so I'll be 'Jenni' through this stage of my life, too. (Plus, I'm not sure I would remember to introduce myself as, or respond to, 'Jen').
Growing up, I always thought I'd like to be Samantha (Sam for short...remember "Who's the Boss"? Sam was cool.). Now, I think I'd be happy with something, anything, more mature than "Jenni".
Know this - should I have children, girls particularly, they will have a much less common name than "Jennifer" was in the late '70s/early '80s. It's too bad kids don't get to choose their own names after a certain age. Of course, then we might end up with a lot of "Frankensteins". Maybe that's not such a good idea, after all.