The median home price in Washington is $601,545. At 80% LTV, the typical loan is $481,236 at the current 6.76% average rate, producing a monthly P+I payment of $3,124. Total interest over 30 years at this rate: $643,579.
Property taxes in Washington average 0.75% of assessed value, or $4,512 per year on the median home. This adds $376/month to your all-in housing cost. When evaluating a refinance, factor in property tax and insurance for a complete picture.
Washington has no state income tax, so there is no state-level mortgage interest deduction. The federal deduction still applies on loans up to $750,000 for itemizers.