I have a big backyard, I lost my virginity there actually and it was a lot of fun, that is now mine and my boyfriends favorite place to have sex. Just make sure you aren't too loud or have neighbors.
my favorite is in a field of tall grass or something ... lay a rug down, and have a leisurely afternoon of sex.
we were almost caught once by some walkers! we heard them though and just laid quietly. they walked past us about 6 feet away! we were naked and still horny too!! good fun!!