Transportation in Swaziland includes only a few options for PCVs: khumbis (15 passenger vans), buses (of small, large, and coach sizes), bicycles, and rides with friends.
I had low expectations for the khumbis after traveling on Ghana’s version called a trotro. Swaziland’s khumbi is usually a variety of steps up. I have yet to travel in a khumbi where I could see the road through the floor, I generally do not feel like the khumbi will fall apart while driving, and more often than not I get to travel on the more spacious Toyota Quantum rather than the old Toyota HiAce.
I regularly ride in a HiAce to and from the office and the Mbabane bus rank. Usually I have lots of belongings and there is no space for belongings on these khumbis. Exiting is never graceful and I usually knock my head on the ceiling at least once.

Inside a HiAce, the older model khumbis used mostly for shorter distances.
The Quantum is much more widely used and is all I travel in at my site. There is usually a space for bags by the driver and the front row has a few more inches of room, which is great when traveling with big bags.

Inside the newer Quantum model.
Unfortunately, though, the conductor (money collector and door operator) regularly overfills the khumbis, so sometimes instead of 15 passengers, there could be 25 passengers. There are also a lot of traffic stops, so conductors get creative in hiding passengers or ditching passengers that are sometimes collected again after the traffic stop.

A look outside to the Manzini Bus Rank.
Sometimes travel by public transport can be fast or it can be excruciatingly slow. Often, the khumbi needs to fill up before leaving the stop, which can take hours. Other times there are so many pick ups and drop offs, that the driver stops nearly every minute to exchange passengers.
It is also best to not watch the odometer while in khumbis. The drivers are often in a hurry, but with picking up and dropping off so many passengers, there is a lot of speeding up quickly and stopping in a hurry. It is always a good idea to have something to hold on to.

The view from the front seat on the road between Matsapha and Mahlanya.
As only a few buses pass my community, and I have not traveled to many other locations in Swaziland, I cannot comment on bus travel, and I also do not have a bicycle.
Khumbi etiquette is complicated. It is usually first come, first served when picking seats. Sometimes Swazis refuse to slide into the bench, preferring to stay on the aisle seat. Sometimes they will exit the khumbi soon, but often not. Sometimes other riders will offer to hold a bag for you or help you on and off with your many bags. Sometimes everyone is rude and ignores you. Sometimes the little kids stare at you the whole ride and are too shy to respond to your questions in siSwati. Sometimes there will be professions of love from passengers or the driver. Sometimes the passengers cannot believe that you can speak (some) siSwati. Sometimes the passengers think you can just squeeze past traditionally-built bomake with 10 bags while carrying your three bags and you just stare them down until they move for you. Sometimes you have to stare down the conductor to get the correct change. Sometimes you just have to be as rude as the other passengers to make life easier. And that’s just how life on khumbis goes.