Yes, in my opinion you always request a Washington State Department of Licensing (DOL) Hearing - even if it looks like the hearing will be unsuccessful. It is worth the $200.00. It is important to remember that this is a "Civil" administrative hearing and the standard of proof is preponderance of the evidence. (alittle over 50%)
However, in the worst case, you get a free deposition (interiew of the officer) under oath. If I think there are no good legal issues - I will always subpoena the officers. I then proceed to use the hearing to find out everything about my client's case while it is fresh in the officer's memory and pin down his/her testimony. I then have the hearing transcribed and can use it later in Court - if there are discrepancies with the officer's testimony. In alot of jurisdictions, charges have not even been filed by the time of the DOL Hearing.