Queen sized with a normal mattress. My bed has both a head and foot boards. Given I'm tall footboards are my natural enemy. Thankfully it has widely placed slats so that at least my foot can slip through, though I do sometimes wake up with sore feet/toes that I suspect is from he kicking the slats in my sleep.

I tried flannel sheets years ago but didn't like them, so I use regular sheets year round. Depending on the season, I add either a down comforter in a pretty duvet or a quilt. In the summer, the top sheet is usually enough by itself.