Planning a successful evening at home doesn't require a lot of time or money. Taking a little time to plan some activities ahead of time as well as a menu is all that is required.

[edit] Steps

Think of fun games that are also educational, or teach kids about morals. This is a great way to weave these lessons into a fun time without making kids feel like they're being lectured by a parent. Below is a free site with many suggestions on activities and games.
Think of both kids' and parents' favorite foods. Make sure you incorporate these snacks into the family night.
Does your family enjoy movies? If so, movies are great! However, remember if you want interaction, you will have to encourage it. One way is to discuss favorite and least favorite parts after the movie is over. Was a part particularly funny or scary? Encourage both kids and parents to explain their thoughts about the movie.
Create some new family traditions. Baking cookies or a favorite dessert is always fun for kids. You could even make the treats for someone else, and let the kids choose who on a weekly basis! Crafts are another fun option.
Gauge kids reactions to games. If they seem to be bored after a while (being easily distracted is one clue), change to something else. Remember you want to keep things fun!

[edit] Tips

Prepare ahead of time by shopping for snacks or ingredients that are enjoyed by all.
Find games/activities ahead of time and get them out of storage or purchase them.
Locate any other materials or resources such as notebooks or paper to record family memories or allow kids to spontaneously create pictures.