A pretty common design category that's used to describe party games is "filler". I've often seen it used as a way of expressing the idea that it's a light game that can be played in about 15 minutes, and serves as a holding pattern between longer games, or a break from more complex strategy games.
However, most of my favorite games tend to fit that definition of 'filler'. I think that a major aspect that draws me to these games is that (when they're well designed) they tend to have really tightly designed mechanics, and fit a lot of interesting choices into a small space. Maybe a better way to think about these games might be "compact", instead of "filler.
Without a doubt, Sushi Go Party! is among my favorite (I'll go ahead and test drive the term here) compact games. It's an expansion of an earlier game, Sushi Go!, but adds several new cards and mechanics. Both games, however, rely centrally on the mechanic of card drafting.
Drafting is being given an option of a number of cards in a starting hand, having to pick a card from that hand, and then play it. A major aspect of strategy is knowing that your opponents will have a chance at the remainder of the cards. Sushi Go makes use of this mechanic through a really clever metaphor of a conveyor sushi restaurant, and assembling one's items ala carte, in order to make the most delicious meal possible (determined by points on the cards). The art does a lot to sell this concept, since it's both beautiful, fun, and mouth watering (if you ignore the anthropomorphism of the food, anyway). What really makes this concept sing is the design of the items. Some items give straight points, some come in sets, while others are races against your opponents. Once you have a decent idea of the gamestate, you might realize that you have no chance of getting three of a kind for big points, but you might also see that you can grab one of the high value racing cards and walk away with an easy six points.
Party! builds on the original concept by including more items. The core design of the game means that it is modular, and can easily be expanded without an alteration to the base rules. Gamewright (the publisher and designer) includes a few pre-made sets (deck compositions that prioritize certain game mechanics), but I could also see it working well with a randomizer, or with custom creations.
I think that what I like the most about the game is that it has very little in the way of instructions, and puts most of the complexity onto easy to understand rules on the cards themselves. That's pretty similar to what makes Dominion (another favorite) such a good game. Complexity comes from interaction, and not from having to memorize complex systems. So, yeah, it's compact.
Sushi Go Party! is available for 20 bucks, and has been a hit across many of the age groups, interest, and skills levels that I've tried. Highly recommended.