I think there's a theme in some of the posts here that I have experienced as well - events where you *do* thinigs - active moving games, crafts, tours, etc. - seem to attract a wide range of ages of people who like to *do* things. Events where people just sit and listen or sit around and eat seem to attract people who like to - or can - do that, and that may be mostly older people who are not very mobile. Even in volunteering - I did volunteer scheduling for several AGs, and you'll see registration fill up first, with older people.
Personally, I have a hard time sitting for hour-long lectures unless I'm super interested in the topic. Last weekend at WeeM, I volunteered for registration for the first time in my 25+ years of being a member - I am a Hospitality volunteer by nature because it's constant moving.
Society now is very mobile - we eat on the run, text on the run, volunteer on the run, change jobs, change our minds, change where we live, and where we spend our time.
Be conscious of how planning meetings are scheduled. We often have retired people who schedule meetings at big sit-down venues that start at 6PM on a work night and last for hours, or a former LocSec who had board meetings at his home that started at 4PM on Sunday and included a potluck, and could go until 7-8 PM. Working people, especially those with children, don't always have time for that.
For young people on the go, or people who have to arrange for rides or sitters - always make sure your events have an end time. Scheduling a lunch from "noon to whenever we get done" may intimidate people who only have an hour. New people may not care to go to a games night that starts at 7, and has no end time. They might be afraid that they'll be stuck there if they don't like it. You can always invite people to stay later if they are having a good time.