Seahawks at 18 I'd say would be more willing to draft OL than one would at 10. Booker, Membou, Jackson, Campbell, Banks, Conerly Jr. These are some of the top OL, at least two or three of them could make it to 18 and I think it would be very tempting for Seattle to take one. Or, Seattle could move down into the 20's, one would probably still be there and you pick up a few extra picks.
At 18, if not OL, it would have to be a player that slipped through the cracks that would be just too tempting to pass up. Taylor Warren (TE), Jalon Walker (LB), Colston Loveland (TE), etc.