The technology boom is pushing its way north up the Pacific Coast, boosting real-estate prices, sparking neighborhood squabbles and creating new demand for luxury homes asking $1.5 million or more.

Real-estate agents say Seattle, the longtime home of software giant Microsoft and online-retailing behemoth Amazon, is attracting more technology firms because it offers a combination of local talent and lower housing prices than the tech centers of California. In the past year, Best Buy, Alibaba and HBO have announced or opened...