Route notes
Why this routing works
This 4-week itinerary is structured as an open-jaw multi-stop ticket: Honolulu to San Francisco, then a separate overland gap before the ticket resumes in Vienna. That break creates flexibility in the middle of the trip while keeping the long-haul flying on one economy itinerary.
With 3 nights in San Francisco, the routing builds in a short first stop before the overland segment to Vienna. From there, the ticket continues with a regional hop to Bucharest and then closes the loop back to Honolulu, which keeps the final return simple rather than requiring backtracking.
For timing, a May departure fits a compact month-long plan well, especially when one section is intentionally left open between North America and Europe.