I have to agree that it seems kind of mean-spirited to trap total strangers into watching your engagement because they happened to be seated near the middle of a row when they went to see a musical or play and people on both sides of them decided to stay and watch the proposal afterward rather than leaving. The steps in Times Square does seem like a much kinder suggestion for those around you (who can then watch or not), while still maintaining the proposal-in-public angle and excitement-of-New-York angle that would be there in a theater.
To add even more public display to a proposal in times square, you could go into that store that is next to the steps (not sure of the name - maybe American Outfitters?) that lets people have their pictures taken and then add a message and display it on their large billboard outside the store that is visible from the TKTS steps. You could go in there separately from your partner, have them make a proposal message to her from you for the billboard, and then sit on the steps together, people-watching, and she could see the proposal message pop up on the giant billboard, at which point when she turns to you in shock, you can propose in person however you want to add to it (e.g. ring or knees or speech or whatever). That would be a very romantic gesture for someone who likes public proposals, but it is still non-intrusive to those around, and it might even result in some nearby strangers cheering for you both when they realize what is happening, if that is the kind of thing you are going for. It could be fun.
Updated On: 12/17/13 at 12:48 PM