Large Transport; Low Wing; 2 Turbojet Eng
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 2
Confusion; Distraction
ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued New Clearance; Air Traffic Control Provided Assistance; Flight Crew Executed Go Around / Missed Approach
Human Factors; Company Policy; Procedure
I was working Local 4 and had multiple departures for 34L and 34R. We also had sporadic arrivals to 34R even though we had a high volume of departures.  I had an aircraft on final to 34R with an aircraft waiting in position on 34R.  I didn't have enough space to get the departure out in from to the arrival so I sent the arrival around.  The ASDE-X warning alarmed as well.  Many factors led to this event.  I don't think we needed to be landing 34R.  There was plenty of space on either 35L or 35R to fit the 34R arrivals but they want to do the RNZ approach so they land 34R anyway.  In my opinion when we have that many departures we shouldn't be mixing in arrivals unless we absolutely have to.  Distractions in the Tower were another cause.  We had tours and extra people that aren't necessary to the operation.  Especially during a period of high volume and complexity. Even with all the people up in the Tower to help nobody caught the aircraft landing 34R being a conflict with the departure.  In the end though the fault is with me.  I should have used my arrival placard in my departure bay to remind me of the arrival like always do.  But for a multitude of reason; some among the ones states above; I didn't.  In the end I sent the Aircraft X around and held Aircraft Y in position until traffic wasn't a factor and then continued working. Less people in the Tower during periods of high volume and traffic.  Don't land on a runway that has heavy departures.  Open up a Cab Coordinator during time of heavy traffic volume and complexity.
DEN Local Controller reports sending aircraft around with aircraft in position; and lack of use of arrival placard for joint use runway.