I'm so sorry for your loss; what a tragedy to lose Bob so young!
For what it's worth, I highly encourage your plan to celebrate his life with the trip. Not only does he sound like the kind of guy who would love to have you carry through the plan for him, but I think you'll find the journey cathartic in as many ways as it may be bittersweet (we did a similar thing after my Dad passed and it really was a good decision for my Mom!).
My sympathies to you and my best wishes as you move into the future; know that many people here send nothing but their best to you & your family!