If you didn't like Twilight, then read Chicagoland Vampires or The Iron Druid Chronicles

I want something more adult

Maybe Twilight was too juvenile for you? If so then I have two books that might be of interest for you guys.

How about Chicagoland Vampires, in this series we accompany Merit a graduate student finds herself one unlucky night at the wrong side of campus where her existence if forever change.

Series: Chicagoland Vampires #1

Publication Date: April 7th, 2009

Publisher: NAL Trade

ISBN-13: 9780345522481

Now reborn as a vampire she has to put books aside when someone is still out to get her. In this series we find not only Chloe Neill’s version of what if vampires came out of the closet in Chicago but we also get to explore other the what would be of other paranormal creatures.

This series is a mix of action, politics, attraction and relationships.
Links to the reviews of Chicagoland Vampires Series:
Some Girls Bite
Friday Night Bites
Twice Bitten
Hard Bitten
Drink Deep
Bitting Cold
House Rules

If you still wish to start slow with vampires and want an adult paranormal book then I suggest The Iron Druid Chronicles by Kevin Hearne, this guy knows how to mix paranormal, mythology and fantasy into one great series while giving it all a modern twist.

Series: Iron Druid Chronicles

Publication date: May 3, 2011

Publisher: Del Rey 

ISBN-13: 9780345522474
This was the book that made me fall in love with Urban Fantasy (other than Harry Potter of course), this is a book that makes you have fun with all the creatures, myths and stories you thought you knew, it give a fresh hair to vampires, werewolves, witches, gods and other creatures that we might stumble upon on this fund ride that Kevin Hearne has prepared for us.

If you are going to read this book then prepare yourself for some good laughs.
Links to The Iron Druid Chronicles:
Hounded
Hexed
Hammered