Your prayer corner should be a place where it's possible to find quiet. Elijah heard God's voice in a small whisper (1 Kings 19:11) and it's likely you'll hear Him better in a quiet time also. Encourage your kids to find a quiet, consistent prayer time for themselves. Even the smallest children (and their parents) should strive for a time in each day that is free of noise.
Your prayer corner should point to liturgical prayer. This is most easily done by simply paying attention to the liturgical colors and changing your prayer table cloths to match vestments and altar cloths at church. Right now you'd want green for ordinary time and in mid-February we'll change to purple for Lent. Red and white are also essential, and you may want rose (for Gaudete and Laetare Sundays), and gold (an optional extra for the greatest celebrations of Easter and Christmas). You'll have lots of flexibility if you can sew a little, but if you don't, you can easily find placemats or cloth napkins in these colors. An added bonus is that the periodic changes built into the Liturgical Year offer opportunities to keep things new and interesting.