I'm offering some general suggestions based off of annoyances from joining gameworlds.
Firstly, the act of joining gameworlds is a huge pain. You don't know how many people are queued for which games. Also, to queue for them, you have to walk all the way over to the gameworld ports and advertise to the entire server to play. This really discourages even queuing for them at all. There is also a 40 player limit to servers, so with so many different minigames and gameworlds, it is very difficult to get into a game.
I think that allowing you to join and view gameworlds from anywhere is a potential solution. Or maybe a button on the inventory to teleport to the gameworld ports and back to your current position from when you teleported. Also, allowing you to queue for games while in your condo would be a fantastic returning feature from Gmod Tower!!!
The Voting System
It currently has players pick a singular map and have a roulette wheel choose randomly. Even if two people vote on the same map, it could still pick another one. Plus, you cannot see what other people have voted and you cannot change your vote. This often results in players playing a map they don't want to.
I think the voting system should be completely reworked if this is possible. One idea is that you get a UI with every map and a check box in the corner of each one. You can check all of the ones you are okay with playing and don't check the ones you don't want to play. Then the most voted maps are selected randomly.
Another idea is to allow players to see what other players have voted and change their map as many times as they want. If a map has 1 extra vote or more, it chooses that map. Otherwise, it chooses the map randomly.
Another thing is hosting games. The host picks the map already. I think that it should be reworked to where you can host a gameworld lobby which can be joined quickly. Once enough players have joined, you vote and then load the map. Although, I'm not even sure this is possible in the Unreal Engine. It's at least a thought.
I find often that players would want to play with the same people several times on the same gameworld, but for all of the reasons listed above, it is really difficult to do so. I think a rematch button would be great. If enough players have clicked it, a map vote begins and you can play the same gameworld again!