Well the nice thing about Galaxy Trucker is that there's three rounds, and at some point pretty much everyone will get some degree of fucked over. So there's that. Personally, despite my love of Vlaada games (the designer who made Galaxy Trucker) I might hold off until you fill out other areas. Galaxy Trucker is a hard one to repeatedly slam in my book, I'd tend to play it 1-2 times a month tops.

Deck building, well, I do always recommend Dominion. It's a very simple game to learn, with a ton of depth, and it has a lot of expansions. The expansions are nice in that they expand laterally, if you will - think Mass Effect versus Pathfinder - having 3 games of Mass Effect gives you a lot of Mass Effect - lateral - but having the entire set of Pathfinder books increases the depth and amount of knowledge you need, blocking new players out. In short I'd say Dominion is just a basic addition to your collection that is quite deep, fast, and fun.

If you want a different deckbuilder, Trains always struck me as the best of the non-Dominion games. Often described as "Dominion with a map" that's... accurate. The map adds a lot though!

If you like Risk, I recommend both Risk: Legacy and Smallworld. Both are good games, and if you have a fixed group Risk: Legacy is AMAZING. You get to build your own game of risk, with the board changing depending on what you do and how you play. You'll get to name places and permanently change the game. It's really cool.

I'd recommend worker placement too, and my favorite intro is Lords of Waterdeep. It has a D&D theme, which is fun, but also isn't necessary to appreciate it. Just a good little game, and the expansion adds a lot too so you won't run out of game.

Another I'll recommend is Legendary: Encounters. It's an Alien's themed deckbuilder that's quite interesting. Hard to describe, but its co-operative, and you can die to chest bursters and stuff. Just overall a really well designed game, if a bit heavier than the ones I've named so far.