My family will be together for the first tome together. We want to take pictures. My family has very tall (6'6") and short (5'2") adults, and 5 kids, ages 1-12. What can I do to make pleasing photos?
A lot depends on the number of people and how formal/informal you want the photos to be.
If everyone is the same size, you end up with a straight row of heads, and nothing is les pleasing than that, so differing heights can work well. Unless the tallest or shortest adults are sensitive about their height, I don't think putting the shorter ones on stools to make them about the same height as the larger adults is the way to go. In a very large group you might use benches and so forth to make many rows of people visible, but with a family shot I wouldn't.
There are endless possibilities. You could have most of the adults in the back, and have a few (perhaps the talles/shortest adults) sitting on the ends of the front row, with the kids in the middle.
You could have the adults sitting and the children standing.
For a fun shot, you could try getting up on a ladder and shooting down on them all. The angle of view would put less emphasis on their differences in height.
I like Anisha's last idea, that could be fun. Depends on the family and how traditional a photo they want.
I've always found that if you cut the tallest weeds down to size (that is, have them sit) and put the tiny ones on laps, everything else gets a whole lot easier, whether the grouping is formal or informal (although I've got to say that I find there's a whole lot of "family" feeling missing with formal groupings unless there's at least semi-formal dress involved). The shorter adults and the taller kids then become the upper limit, and the kids that are too tall to sit in a lap without obscuring the lap's owner become the lower limit.
That leaves a lot of freedom to arrange people, and makes it more likely that their place in the picture might somehow be related to their place in the group. And even if the arms of armchairs or (my natural urge is to type "Chesterfields") sofas are normally off-limits for sitting, they can help to raise or lower people and underline their relationships. If you can come up with an arrangement that looks as though it might have happened naturally, take a few bonus points for yourself -- it will beat the heck out of something that looks like a mid-nineteenth-century cabinet tintype with the family all strapped to those posing coat-rack things they used in the day.
How about making the short adults sit on a bench, and the taller adults stand behind them, with kids sitting on the ground near the feet of those on the bench?
Make the short ones stand on stools so that they look near equals to the taller ones, while you take the pics without showing their feet.
For fun make them stand in a row in the increasing of their heights, while you take the pics from the ground level POV.