Choose a favorite place—whether it is a fountain, hotel rooftop, monument or national park—that has personal significance to the two of you. Once you are there, ask someone nearby to take a picture of you together. Instead of posing, drop down on one knee.
Plan a romantic destination getaway for two. When you're on the plane, use the loudspeaker system (of course, run your plan by the flight attendants first) and propose at 35,000 feet.
Pick the perfect spot to propose and have a photographer hide somewhere discreet. After your proposal, your photographer can snap some posed photos too.