You'd be surprised... Thursdays will still be fun either way.
In westport check out:
Kelly's - chill irish bar
Dark Horse - also laid back
Firefly - also laid back
The Foundry - Bar/Restaraunt
The Union - crunchy beatz bar
Plaza you should go:
Gran Faloon - "college crowd" style bar
O'douds - Good irish bar
The Point ($10 all you can drink friday from like 7-10PM) this is like a block north of the plaza though.
Those would be my suggestions. I'm 29, and I thought I saw you mention you were younger in another thread. You won't run into a bunch of dads at all these places (sorry for the dads on here