We decided to get married when UK immigration decided it was time for me to leave the UK! There was no romantic proposal or anything traditional about it, but it worked out for the best. We were naive and pretty unfamiliar with the visa process, so we thought there would be no issue if I came over on a fiance visa and then applied for an extension. They didn't have the requirement to prove wedding plans at that time. We learned our lesson when my extension was denied and we only had two weeks to get married (I didn't postdate my fiance visa, so was only in the UK 3 months before it expired). We were unsure about what the exact plan was, so we ended up going to book an appointment for a registrar's office ceremony 15 days in advance, then telling our parents four days before the ceremony. It ended up being a beautiful, memorable day, and was actually exactly the type of low key wedding I wanted. We had a few friends who were far away and angry that we didn't have a wedding they could attend, but in the end, it was our day and it was what we wanted.
The one problem with LDR's, at least in my experience, is that you don't spend REAL time with that person when you're together. You almost put on your best behaviour when you're together, because you want that short time you have with them to be perfect. When you're finally together, living in the same place for the first time, it's like a shock to your system. You have the real person, not this person you've built them up to be in your mind, or who they've tried to show you they are during your limited time being physically together. They're not ONLY the perfect, sweet, attentive person you love - they turn into who they really are. In my case, this was a sweet, caring person, who was also messy, immature, and a video game addict. Luckily, we met at university and were best friends, so I already (kind of) knew who he really was, but the transition was still very difficult. It takes a lot of adjusting, and unfortunately for those of us in a trans-Atlantic relationship, you have to make a pretty huge commitment to them before you spend this "real" time together. Basically, I would say to anyone in an LDR thinking about getting married - make sure when you are together, you're yourself and not who you think your GF/BF wants you to be. Be messy, fart, burp, scarf down an entire pizza, speak your mind, be completely honest, and do whatever else you'd do once you're together for good. It's better to figure these things about before you spend hundreds on visas and flights, and your stuff has been shipped over to the UK, making it nearly impossible to just break up and go back home. Not to say that this is true of all LDR's, but a relationship with a handsome foreigner may seem incredibly romantic and exciting right now, but it will soon lose its initial appeal and you'll just be in an ordinary relationship, so make sure this is someone you'd date and want to marry even if they lived down the street and you saw them everyday.