Need help with potential problem tenants for a brand new landlord

[James Ayers]

We're very excited!  Today my wife and I just signed the papers to take ownership of our very first investment property; a duplex in Keizer Oregon (a suburb of Salem).  Thanks to this wonderful community and all you wonderful people over the past few months my wife and I have gained the confidence to pull the trigger on this exciting adventure.  Now that we're here we get to start the fun with our inherited tenants.  

From what we've gathered our tenants seem very similar to the angel and devil on the shoulders of the cartoon characters we used to love watching when we were kids.  The "angel" tenant is a single dad who is a handy man and seems like a great guy who keeps his property clean and in good shape.  On the other side the "devils" are section 8 tenants who don't keep their property clean or in good repair (holes in the wall / broken doors / damaged cabinets / etc.) and seem to be the black sheep of the neighborhood.  The two neighbors that we've met have both complained about them, saying they smoke marijuana in the garage and are generally "rowdy" (kids throwing rocks at cars, garage seems to be some sort of default "hangout") in an otherwise nice family neighborhood.  

So finally my question:  We want to get rid of the tenants when their lease expires at the end of January, but we're not sure how to do this.  Can we just jack their rents up much higher than the other tenant's rent, despite the property being in poorer condition?  Can we just tell them we don't want to renew and they need to move out at the end of their lease without giving them a reason?  We would love some advice from those who have dealt with a similar situation in the past.