When controlling SEA_APP some A/C arrivals are destined for the Major Satellite airports such as, KTIW, KPAE, KTCM, KBFI, KOLN and KRNT.
If they require radar vectors for an ILS, I then have to look at my airport diagrams/charts to determine which Runways (not forgetting the wind!) and what are the Base Leg headings for these Runways. I always like to keep the approach smooth and gentle for the passengers LOL.

In my research, I have found that the Base Leg headings only slightly differ between all of these airports (050 – 080 and 230 – 260) so, I have decided – for expediency - to adapt a policy which provides me with a confident approach.
If I use the KSEA Base Legs (070degs and 250degs) for ALL of these satellite airports then I am happy that the approach is reasonably suitable for the appropriate PTAC to be delivered.
Happy controlling

Peter