Some board games are great for game night. They take less than an hour to play and provide a lot of fun. Other board games are equally as fun but take a lot longer to finish a game. These long gaming sessions mean that game night is dominated by one game. That may be fine for some but others may not be too keen on playing the same game all evening.
Most board games that take many hours to play also have a lot of rules. To speed up game play, make sure everyone knows the rules beforehand. If you are teaching someone the game as you play, then the game will take a lot longer to finish. A new player may wish to sit out a game and observe. They can familiarize themselves with the game and rules without slowing down an already long game.
If a game is likely to take longer than you have time allotted, consider playing the board game at a table where the game can be left out and remain untouched. This way you can just leave the game out until play can resume. A lot of people play Chess by leaving their game set up on the board and play a move when they have time.
This may not work if you use your game space for another function. You can always take pictures of the board game set up and then put away the game. Refer to the picture to set the board back up. You can also write down what each player had in front of them - whether it is game money, tokens, special cards, etc. Before taking a break from a long game, continue to play until it gets to be the first player's turn. Write down the order of players so everyone will remember where they should sit.
While playing a really long board game might appeal to some folks, others will not appreciate the time it takes to finish just one game. Those same people might enjoy playing an extremely long board game over a couple of sessions. It will help new players get to know the game better - making the next epic game a little shorter.
Longer board games can be a lot of fun to play. If your group does not have time, then consider playing for a while and then saving the game for a later time. There might also be rules for a shorter game - so check for options either in the rules book or in online forums.