I also recommend keeping the weight reasonable - too light and recoil becomes an issue.
My wife is 5'7" and about 135#. Her two shotguns are a 20 gauge Beretta 303 semi-auto at 6#10oz and a 20 gauge Beretta 471 SxS at 6#8oz. When she first got the 303 she complained a little about how "heavy" it was but after lessons with an instructor on how to properly handle it she has not made any issue about their weight. Because they are not unduly light recoil is a non-issue for her with either gun and our 3/4oz target loads, 7/8oz target/quail loads or 1oz pheasant loads.
The 303 has a 26" barrel and the 471 has 28" barrels. I believe that properly fitted is more important than weight and both guns have been fitted to her. She seems happy to shoot them, well, at least this looks like a smile on her face when she shot the very first bird of her life and of 11 that day. This first hunt of her life was this past February and tomorrow she's sending the deposit to Rio Piedra for a hunt this fall.