It sounds like an awesome trip. In Seattle you really should see Chihuly glass next to the space needle
www.chihulygardenandglass.com. If you can get there before dusk and spend an hour watching the outdoor garden transform from daylight to the night lights.I found the Boeing tour a bit sterile with a long bus trip, a wait before the tour and then a collection of big planes in partial assembly.
If you are planning on a trip to the Grand canyon, I would recommend the South rim. We stayed a few nights in LV, then caught the complimentary bus to Boulder City Nevada. We left our suitcase with airline company as they will only take small bags and flew to the south rim. There is a 15 min taxi to the National Park lodges and once there you will find a good regular hop on/off bus service up and down the rim. we stayed the night, flew back after sunrise and breakfast, picked up our suitcase, caught the bus to Las Vegas airport and flew out. The main issue was getting accommodation at the south rim, but the rest was easy.