Good games have been mentioned already, but my kids also liked Uno Choo Choo, Hoot Owl Hoot, and Thomas Making Tracks Game.
The Uno Choo Choo is really a color/animal matching game and we slightly modified the rules to make it less about winning or losing. Plus they like to press on the train to eject the card.
The Hoot Owl Hoot game is a cooperative one where the players are trying to get the owls to the nest before the sun rises. It uses colors to play (similar in to the way Candyland uses colors for movement). You can change the difficulty by changing the number of owls you play with. I have 4 year olds that started playing the game at 3. They mostly decide which owl to move based on which color they like at the time so it's a little helpful to have an adult play to get the owls home. But it's still fun and sometimes I rig it a little by removing some of the cards that makes the sun move. :-)
The Thomas Making Tracks Games has 2 parts. First you use a spinner to determine what pieces you use to build up your track. Then you use the spinner for colors to affect your movement.
Their other favorites from the ones mentioned already are Zingo, Don't Break the Ice, Connect 4, and Don't Wake Daddy.
If I were going to be 3 games that have been their most favorite, I'd pick Hoot Owl Hoot, Zingo Bingo, and Thomas Making Tracks.
You could also do some puzzles. We have a few of the large floor puzzles that are around 40 pieces or so. The puzzles may be a bit tough for the 2 year old, but you can help out by directing which piece and where.
Also, you could do some playdoh activities if they are into that kind of stuff. I have one kid that is more into than the other so it's hit or miss for us.