Wetsuit sizing

Hey all, Ive been looking at wetsuits online and found a few that I like and hope to purchase within a month or so, but when I look at the sizing charts I either fall into the cutoff size of a medium or the starting size of a large. Is it better to have it tighter and go with a medium or have it a loose and go with a large size, and if I go with a large will it be way to loose. My personal specs are 5'9,150lbs,32 inseam,32in waist. Someone has been gracious enough to offer a spring suit up to me so I can least attempt to hit the salt now and I think I will at least throw my waders offer it as a second layer that I could strip off if I were to take a plunge and they fill with water. But I would like to get a better covering suit in the future.
Thanks as usual
Flip....

I am close to your size 5'9" and about 164lbs with a 34" inseam and 33" waist.
I found some great deals online on farmer johns but, decided to go down to Pacific Outfitters and try some on.  I usually wear a medium but, it was too tight to be comfortable for a day of fishing and sitting. So, I got a large and it is snug enough to keep extra water out but, very comfortable all day. 
Good news is they had a sale for $69.00 for 3mil FJ (down from $99.00).
My suggestion is to try some on if at all possible and try sitting on the floor to see how it feels in that position. You can always order the same brand and size you try on if you can't find a walk in store deal.
Remember you will probably want a little room for a rash guard or underarmor type shirt underneath for warmth and comfort.