We used to eat out a lot (fast food), mainly for convenience. Both DH and I work full-time and with the kids' evening activities, things can get pretty busy.
However, in the last 6 months, we've really made a conscious effort to cut back. Not so much for the financial aspect, but because it's not healthy to eat that much junk. I've been trying to plan my meals better and when I succeed (eat at home all week), we've been "treating ourselves" to a sit-down meal at a restaurant on the weekends.
Although restaurant food isn't usually as healthy as at-home cooking, eating one meal per week out instead of 3-4 has to be better. The sit down restaurant is much more enjoyable than running through a drive-through... and, honestly, it's saving money, too. (3 fast food meals at $12-15 each, versus one sit down meal of about $25.)