Dobble (small enough to take travelling too!)
Qwirkle
Exploding Kittens (although we have the NSFW version which is funny after a few drinks!)
Farkle (just need 6 dice, a pencil and paper)
New Market (normal pack of cards and some play pieces, can be anything - buttons, pennies, whatever you have laying about)
With kids you can't beat some Top Trumps really in terms of easy to pack, quick game etc.
Cousins girlfriend introduced us to a game while abroad last week. All the players have about 6 small scraps of paper each and write anything on each piece (can be an object, saying, place, person etc.) then everyone folds each of their pieces in half and adds them to one communal bowl. Split into teams. Set a one minute timer for each round.
Round 1: A player from the team going first takes a piece out of the bowl and has to describe it without saying any words actually written down on the paper and their team has to guess what it is (E.g. Penguin - a black and white flightless bird that lives in the cold). Once the team guesses correctly keep taking pieces out of the bowl and describing until the timer runs out. Keep a score of how many were guessed correctly. Then Team 2 takes their turn. At the end of the round return all pieces to the bowl.
Round 2: Repeat of above but the player can only say ONE word to describe the paper selected from the bowl (e.g. Penguin - Bird)
Round 3: Repeat of above but the player can only ACT the paper selected from the bowl. No words/describing (E.g. Penguin - waddling like a penguin 
)
^^ that game actually turned out to be super fun (after a few drinks) and we ended up playing it a few nights!