The plan was to visit Mae Sai from Chiang Mai, and cross into Myanmar for couple days just so I could say "I've been there". Well, it didn't work out that way at all.
When I first got off the bus, I could tell that things were very different here. To start with, the people weren't Thai - they were mostly hill tribe people or Burmese. The other thing I noticed was that there was plenty of soldiers in the streets, and these looked like real soldiers, not at all like the ones you usually see in Central Thailand.
Mai Sae is right on the border - that is, the city literally goes right up to the river that forms the border, and then the Myanmar city of Tachilek is immediately on the other side. There is a large hill on the Thai side of the border, and I chose a guesthouse on the side of this hill that overlooked the river and into Myanmar. It was quite a nice view, although it was a bit of a climb to get to my guesthouse when I was out during the day. None of the guesthouse staff spoke Thai - they spoke Burmese, Chinese and a good amount of English. Several of the staff had grown up in Christian Missionary schools in Burma, which is where they learned English.
There is a hill near the border crossing with a temple on top. The temple has this huge statue of a crab on top - I'll try to dig up a photo of this later. It was quite a hike to the top, but again, there were good views all around.
Of course, the border crossing was closed, and so there wasn't much point in visiting. Apparently, there had been some shooting back and forth across the river, which is why the border was closed, but I didn't feel unsafe. There were a few tourists who came in by tour bus during the day, but at night, it was pretty quiet.