When my DH proposed, he did it in front of 400 hundred people (including my bosses and co-workers at the time) at a charity ball we attended. I had no idea he was going to do this...he snuck away and went up to the bandleader, took the microphone, tapped it and said "Can I have everyone's attention, please?" Everyone stopped what they were doing, and he walked up to me (our table was right next to the dancefloor) and got down on one knee. I thought I was going to die right there! Total strangers started clapping and yelling "say yes!" I did, and then the orchestra started playing a song for us to dance to. It was embarrasing, but very romantic!
We also spent our first Christmas (15 years ago) in New York City. We were dating at that time, and our exes had picked up our respective kids for the day...so we had absolutely nothing to do the rest of the day. DH secretly called the airlines, booked a hotel and took me to the airport (we were supposed to be "meeting" someone who was coming in for the holiday). When we got there, he parked the car in the short-term garage, which struck me as odd. We went into the terminal and ended up getting on a plane (I was in total shock). We literally went with the clothes on our back (all I had was my bag and a coat - we had to buy gloves at a little market near our hotel!). It was totally spontaneous and a lot of fun!