I would sell all my bitcoins if the price reaches to $1k, as that is the price I have kept in my mind since long time, and once it reaches there I won't hesitate in selling.
I find it a bit strange that so many folks seem to be focusing on $1k as a sell point, yet I doubt that $1k will actually be the top of any peak, including the fact that BTC was already at nearly $1,200, and therefore, if history is any indication, it is quite likely that BTC will shoot passed $1k - once it gets to about $800-ish.. so either selling before $800 or after $1,500-ish would be more prudent.
On the other hand, if you are nervous about missing out on the peak, and you believe that $1k could be the peak, then it may be prudent to sell some reasonable portion of your holdings at $1k and then additional portions at points thereafter, but still at a level that is ultimately comfortable for you... while exercising some moderation and prudence.