I almost proposed to my fiance there last spring. The biggest issue is the goose droppings. There are a lot there. I was going to lay down a picnic blanket under the tree with a great view of the Washington Monument. I was going to bring wine, a bagette and cheese. The best bagettes are at whole foods. They are just fresher than everywhere else I tried. I didn’t end up doing it there because my fiance was in New York and it was still too cold the weekends that she came down. I always imagined proposing to her on one of the first days of spring. I ended up doing it on a secluded beach on Cumberland Island in Georgia.
A couple more things.. it’s most romantic during dusk but be aware of the helicopter that circles the Mall area. It seemed to come around every 5 minutes or so. You don’t want that to distract from your proposal.