Large item is "featured" item. Possible video or image. Featured shows at top of archive.

Home shows anything today, sorted by date ascending into the future. Archive shows all events in descending date order. Date field defaults to date posted. Featured image and video (youtube link/id) available for each item. 

if (featured item && has_featured_video ) {
display large video player on homepage
} 
else ( display normal featured image) 
{
}

Date only, or date & time?
Single date or range?
Display on front end, or only used to for sorting?
previous/next/archive like message of the week?