This is more general advice in case you’re unaware. The TP benefit is in number of segments not distance, although distance of each segment is a factor. Most of the cheaper fares I’ve seen allow 2 changes either side of the Atlantic. I don’t know if there are direct flights from Dublin to Helsinki, but a good route is start to HEL, then LHR, JFK, LAX and then Seattle. This typically yields 880 TP in business and domestic first. Look at the TP Run wikis and the SH+ and routes over 2000 miles.