is Site 001 the only site that runs Seattle Police? or does any of the other sites push their feed through too?
Sites are definitely localized. For example: on Site 001 (Columbia Tower) you will get 100% of Seattle city TGIDs. On Site 003 (EPSCA) you'll hear the primary SPD Dispatch channels but not the city of Seattle groups. The reverse is also true. You will hear NORCOM dispatch on Site 001 but you won't hear the City of Bellevue channels.
For such a large system like KCPS, it's best to break down what you want to hear and then work backwards. Figure out what TGIDs you need then figure out the site and then create your quick key.
In my scanner, I've always had a dedicated quick keys for specifics sites -- such as Columbia Tower and KC/Valleycom. Both of those are in ID SEARCH mode but I lockout the non-Seattle or non-KC TGIDs so I don't receive that traffic.
Since I live on the Eastside, I'll have EPSCA programmed in with the NORCOM channels but in ID SCAN mode. This is just makes the searching faster and keeps everything limited to my local area. This is only system I have in SCAN mode. With smaller systems (such as Port of Seattle) you could always use SCAN mode. They don't add new channels very often.
The 436HP has a huge memory so you can create many Favorite Lists with multiple sites. This does make it a little more flexible than the older Uniden scanners.
For 436HP owners, I can post my Sentinel HPE file if anyone is interested.