I agree on my back in the bed or sitting in a chair is the best for me. My bed is good but there are a couple chairs around the house that are good too. I like to throw my legs over the arm of the chair and lean back. Unless of course I am riding a dildo which I like to do...For sex I like almost any and all positions...not too picky on that....

totally naked and exposed - many times end up with a pillow under my ass my eyes in the eye of my pussy coming down the line together

masturbating-in bed normally with a toy or in the shower with the shower massage
sex-definitely from behind hard with my ass in the air while i get spanked with each thrust

For masturbating I prefer to be laying in bed with my legs spread and my butt elevated a little by a small pillow. The little bit of elevation usually makes some of my toys a bit more enjoyable.

For sex, my favorite position is on my back on the edge of the bed with my legs hanging over. Not exactly sure why since there are so many great positions but that one always seems to get me that little bit extra excited.

For masturbating: definitely on the bed. More space and options to move around - normally either just on my back, or sometimes laying on my front.

For sex: it varies so much. Sometime i want to be in control, and I like being on top, either straddling normally on squatting so i can move around on him, other times I like to be dominated and have him on top of me missionary or from behind. I am a big fan of being on my back with my legs up high so he can get in very deep.

for masterbations I love to lay on my bed with 2 pillows under my neck and let my fingers do the work . Sometimes toy but as much as just fingers

For sex i love to take him from behind, I love to be the bad girl and let him give it to me hard .Pulling my hair a little can also be fun. But i also cum harder when I get it from back there.

For masturbation with my fingers I prefer sitting in one of my chairs, leaning back with my feet up on the desk or table.

with toys I'm usually either laying on my side or straddling it while it rests on a chair.

for sex with guys I love having him on topmy legs up on his shoulders

Can I interrupt to say how exciting this thread is? And how exciting that girls like the Missionary. It's exciting to be on top and have her pinned under you. And it's so exciting to see a girl at the moment of sexual "surrender" when she spreads her legs. But if she lifts them high and wide when she spreads them, that is INCREDIBLY AWESOME. A guy could cum before he even snuggles into that beautiful big saddle.