Agree with pretty much everything said. Bitter with Columbus only. The only other advice, if you want a fifty/fifty ratio of flavor/aroma I'd adjust to something like 60%columbus/40% citra or 65columbus/35citra. Citra, in my experience is a lot more potent flavor/aroma wise and can easily overpower other hops in later additions. I'd go 60/40, taste it before you dry hop and adjust if you want to pull the smell one way or the other.