I've been fortunate enough to take quite a few trips to Singapore over the years.
The research trip.
I had been in KL for nearly three months on a 90 day visa and needed to leave the country overnight. Singapore was just a bus ride away.
One of the best things about living in KL while I did my research was that when I realised it'd be helpful to have some pictures of the Merlion for my thesis, I was able to pop down for a couple of days.