My setup is that I have a small locked case that I am putting into my larger suitcase.
Delta in SLC has me fill out the declaration and put it INTO the gun case and lock it. They take me over to TSA who does a "wipe down" test for who knows what. I guess by transporting a firearm I am now more interesting than the average Joe. TSA does not notice that they can't see the declaration. I make it to SEATAC with the bag. All is good.
Return trip. Delta SEATAC has me fill out the declaration and put it INTO the gun case. I take my own bag over to TSA. The guy asks me where the declaration is. I tell him that it is in the case. He looks at me like I'm a moron, has me open the case, remove the form. He then informs me that the form should be placed on the case so if the suitcase is selected for additional screening, they won't have to cut open the case. Made it to SLC with the bag. All is good.
Seems to me that if I show up telling them how they are supposed to do their job I'll get selected for additional screening, strip searched, and thrown in jail for a few days...
Other than that, carrying in Washington state was awesome.